Accumulated Depreciation Amount is ignored when run depreciation

 Hi,

I need to convert an asset which has a 7 year STL depreciation schedule. It is placed in service in Jul-06 and should be fully reserved in Jun-2012. The original cost is 107860.22. Based on 7 year STL, the monthly depreciation should be 1284.05. However, by the end of 2009, it already had 74164.75, which means, in the rest of its asset life, the monthly depreciation should be 1122.65 ((107860.22-74164.75)/30). I entered depreciation reserve as 74164.75 hoping to bring down monthly dep exp. to 1122.65. But when depreciation runs, it still take 1284.05, not 1122.65. Is this the intended functionality? Is