SAP Message AA164 - Special dep. not allowed in depreciation area & (Correct dep.key)

Diagnosis In depreciation area &V1& you have entered the depreciation key &V2&.This depreciation key is used to calculate special depreciation.No special depreciation can be calculated in depreciation area &V1&, asa result of the chart of depreciation in area &V1&. System Response The system does not allow this depreciation key. Procedure Correct the depreciation key in depreciation area &V1&.