JUSTICE McLAREN delivered the opinion of the court:

Petitioner, the Kendall County Board of Review (BOR), appealsfrom the decision of the Illinois Property Tax Appeal Board (PTAB). Respondent and cross-petitioner, AT&T, cross-appeals from the sameorder. We affirm.

AT&T operates a telecommunications facility and trainingcenter on a 15.48-acre parcel of land in Kendall County. Theparcel is zoned for agricultural use with a permitted special useas a telecommunications facility. Various buildings erected on theproperty, including a 62,000-square-foot underground building, total approximately 97,000 square feet. The property received a1999 assessed valuation of $79,690 for the land and $1,765,700 forthe improvements, for a total of $1,845,390. AT&T filed acomplaint with the BOR, which denied relief and left the assessedvaluation at $1,845,390. AT&T then appealed to the PTAB. After anevidentiary hearing, the PTAB determined that the fair market valueof the property in 1999 was $2 million, and the assessed valuationwas $61,438 for the land and $602,762 for the improvements, for atotal of $664,200. The BOR filed a petition for review with thiscourt, and AT&T filed a cross-petition shortly thereafter.

The BOR first contends that the PTAB's decision and finding offair market value were against the manifest weight of the evidence. The findings and conclusions of an administrative agency onquestions of fact are to be held prima facie true and correct. Oregon Community Unit School District No. 220 v. Property TaxAppeal Board, 285 Ill. App. 3d 170, 174-75 (1996); 735 ILCS 5/3--110 (West 2000). This court may not reweigh evidence or make anindependent determination of the facts, and we will not disturb anagency's findings of fact unless they are against the manifestweight of the evidence. Oregon Community Unit School District, 285Ill. App. 3d at 175. A finding is against the manifest weight ofthe evidence only if the opposite conclusion is clearly evident,not if an opposite conclusion is reasonable or if this court mayhave found differently. Oregon Community Unit School District, 285Ill. App. 3d at 175. In addition, weighing evidence anddetermining the credibility of witnesses are jobs of the PTAB andare uniquely in its province. Oregon Community Unit SchoolDistrict, 285 Ill. App. 3d at 175.

AT&T presented J. Edward Salisbury, a real estate appraiser,as its expert valuation witness. Salisbury testified that heapplied both the sales comparison approach and the cost approach todetermine the value of the subject property. Under the salescomparison approach, Salisbury took into account the recent salesof eight AT&T parcels with underground buildings in various partsof the country. This approach led to a value for the parcel of$800,000. Under the cost approach, Salisbury estimated the valueof the land at $185,000, based on sales of other properties inKendall County and surrounding counties. He then determined thevalue of the buildings by the replacement cost method, whichdetermines the current cost of erecting a building of the samedegree of utility as the existing structure. This method produceda value for the buildings of $10,354,737. He then calculateddepreciation of the buildings. Using five of the properties fromhis sales analysis, Salisbury concluded that the subject propertywas subject to an annual depreciation of 3.5% and a totaldepreciation of 94.5%. This produced a depreciation amount of$9,785,226 for the property, leaving a net value of the buildingsof $569,511. When this was added to the value of the land, thetotal value of the property, under the replacement cost method, was$754,511. Salisbury gave more weight to the sales comparisonapproach and stated that he believed that the value of the propertywas $800,000.

Salisbury also opined that the highest and best use of theproperty was commercial use as a warehouse. This opinion was basedon the assumption that the county "would consider" changing thecurrent zoning. Under the current agricultural zoning, thebuildings would have zero or negative value, as they had noagricultural use and would need to be torn down. In addition, theproperty would not sell as a telecommunications center.

AT&T also presented the testimony of its tax director, DenisDuvoisin. According to Duvoisin, AT&T no longer built undergroundstructures such as the one on the subject property, and suchbuildings had no functional utility for contemporarytelecommunications. AT&T still used the building as atelecommunications facility, and there were no plans to replace theunderground building with an aboveground facility.

The BOR presented the testimony of Donald B. Johnson, anindependent appraiser. Johnson made his initial appraisal as ofJanuary 1, 2000, and then estimated "what was there" on January 1,1999, because AT&T did not provide him with all of the informationthat he had requested. Johnson determined that the highest andbest use of the property was as a single-tenant communicationscenter; that use was already legally permitted, the site hosted theconfluence of five major fiberoptic cables, and any other use wouldrequire demolition of the improvements on the property and approvalby the Kendall County Board.

Johnson opined that the fair market value of the land was$185,000. In determining the value of the improvements, Johnsonused the reproduction cost method for the control building and thereplacement cost method for the remaining structures. Thisresulted in a total value of all improvements of $6,954,359. Johnson then determined depreciation for the improvements, usingthe Marshall Valuation Service and some adjustments for functionalobsolescence. Different depreciation percentages were applied tovarious portions of the improvements. This resulted in totaldepreciation of $2,940,271. Subtracting the depreciation from thevalue of the improvements, Johnson determined a net value ofimprovements of $4,014,089. Adding the value of the land, the fairmarket value of the parcel was $4,199,089.

The PTAB found that the main building on the property wasunusual and difficult to value, as was demonstrated by the "wildlydivergent" values found by the two appraisals submitted by theparties. The PTAB also found that Salisbury's determination thatthe highest and best use of the property was as a warehouse was"incorrect," as the property was not zoned for such a use and therewas no evidence of a reasonable probability of rezoning in the nearfuture. Thus, Salisbury's appraisal was to receive reduced weightwhere it conflicted with actual zoning. In addition, the PTAB alsofound Johnson's highest and best use analysis to be flawed. Johnson had opined that the highest and best use was as atelecommunications center. However, Duvoisin had testified thatthe telecommunications center would not be purchased by anothercompany because competing systems would be incompatible. Furthermore, there was no demand for such a building, as governmentregulations no longer required such buildings to be underground. Salisbury's sales statistics for other undergroundtelecommunications centers revealed that all of the centers weresold for uses other than as communications centers. Thus, the PTABalso accorded reduced weight to Johnson's highest and best useanalysis.

The PTAB agreed with both appraisers that the value of theland was $185,000. As to the improvements, the PTAB foundSalisbury's cost approach as to the underground portion of the mainbuilding to be best supported by the record and valued that portionat $7,088,983. As to the aboveground section of the main buildingand the other buildings, the PTAB found Johnson's costs moredetailed and complete and used those figures, resulting in a valueof $193,675 for the aboveground portion of the main building.

The PTAB also noted that the appraisers' "vastly differentdepreciation analyses" resulted in values that were $4 millionapart. The PTAB again found that Salisbury's analysis regardingthe underground portion was better supported, and it applied adepreciation rate of 92.7%, the highest such rate Salisbury foundfor a comparable property, but less than Salisbury's estimate of94.5%, and determined that the net value of the underground portionwas $517,496. The PTAB concluded that, because the abovegroundportion of the building was new, no depreciation should be taken. Adding the previously determined value of $193,675 for theaboveground portion to the depreciated value of the undergroundportion resulted in a value of $711,171 for the main building. Asto the other buildings, the PTAB agreed with the depreciated valuesprovided by Johnson, with the exception of a training center thatthe PTAB concluded should have been functionally depreciated by anadditional 15%. Therefore, adding together all the depreciatedvalues, the PTAB found the value of the property to be $2,149,476.

The PTAB noted that neither appraiser had valued the propertyunder an income approach, and it accorded little weight toSalisbury's sales comparison approach, as the sales that wereprovided were not comparable in size or zoning. Salisbury's salesanalysis resulted in a value of $1,460,750. The PTAB found thatthe subject property had more features and new construction thatwere not accounted for in the sales analysis. However, the PTABthen found that the subject property had a value of $2 million asof January 1, 1999, and applied the three-year weighted averagemedian level of assessments for Kendall County of 33.21%. Thecorrect assessed valuation of the property was found to be$664,200, which was comprised of $61,438 for the land and $602,762for the improvements.

The BOR argues that the PTAB's decision is against themanifest weight of the evidence because the PTAB used an impropermethod of evaluation. According to the BOR, the PTAB improperlyrelied on the sales comparison analysis contained in Salisbury'sappraisal for use in determining the value of the property and thedepreciation of the underground portion of the facility. The PTABfound that Salisbury's determination that the highest and best useof the property was as a warehouse was "incorrect." However, thePTAB then used one of the sale properties from Salisbury's analysisin its own analysis, even though that property had a highest andbest use different from that of the subject property, was sold fora purpose incompatible with the subject property's current zoning,and its current zoning was not known.

There are three basic methods of property valuation: (1) thesales comparison approach; (2) the income approach; and (3) thecost approach. Residential Real Estate Co. v. Illinois PropertyTax Appeal Board, 188 Ill. App. 3d 232, 242-43 (1989). None of theapproaches is conclusive evidence of value, but each is a factor tobe considered. Residential Real Estate Co., 188 Ill. App. 3d at243. The PTAB explicitly stated that it accorded "reduced weight"to Salisbury's appraisal "where it conflicts with the subject'sactual zoning," "little weight to the conclusions in Mr.Salisbury's sales comparison approach," and only "some weight" tothe property in the sales analysis, "as there is little in therecord that can be relied on without any rezoning researchdeveloped by the parties in this record." It is obvious that theBOR's characterization of the PTAB's consideration of this propertyas "reliance" is not accurate. The PTAB was not prohibited fromconsidering the sales analysis property, and it exercised itsdiscretion by granting the property limited weight. The BOR citesno case that prohibits the PTAB from giving such a comparisonproperty any weight at all. We find no error here.

The BOR next argues that AT&T failed to meet its burden ofgoing forward under the PTAB's rules; therefore, the PTAB shouldhave confirmed the BOR's original assessment. We disagree.

Section 1910.63(b) of the PTAB's regulations provides that thecontesting party must "provide substantive, documentary evidence orlegal argument sufficient to challenge the correctness of theassessment of the subject property. Failure to do so will resultin the dismissal of the appeal." 86 Ill. Adm. Code