Depreciation Should not Calculated after Useful Life

Dear All,

I have created one depreciation key for a particular depreciation area, which is different from 01 Book Depreciation Area and the default depreciation key.

Depreciation Area          Depreciation Key          Useful life

01                                   ZDEP                         10

15                                   ZDEP                         10

32                                   ZDEP                         10

34                                   NNWB                        15

as per the above details i have different depreciation key for area 34 and useful life is 15 years, i want to calculate depreciation till useful life as 15.

I have created one multilevel method for that depreciation key that KNB, for which i have taken base valuation is 24 Net Book Value, so depreciation is getting calculated for the whole period which i will select in year range for comparisons in AW01N, and if i will take base valuation is 01 acquisition value so depreciation will be calculated as per useful life od 01 depreciation area 01 for only 10 years.

so please give me the solution how can i calculate depreciation for 15 years for depreciation key NNWB.

Regards,

Deepak Pagare