Asset Depreciation Adjustment

Dear Friends,

User has capitalized one asset with wrong assignment of depreciation key 10% instead of 20% on fiscal year 2006.

Depreciation was posted till April 2009, can anyone let me know how to correct this depreciation.

I was tryied to pass manual depreciation T. code ABMA but system do not allowed me to post manual depreciation configuration settings for depreciation key was not set for this activity.

Please let me know how solve this issue and post the correct depreciation which was 10% instead of 20%.