Wrong Depreciation Calculation

[navson]

Dear All
I am facing a issue .i.e asset depreciaition for the first period is on Orignal cost instead NBV,viz,

Asset Cost 20,000

Date Place in service 31st july 2008

Depreciatiion method Diminishing Balance Method ( 10%)

Asset is added through quick addition in sep 2009

Accumalated Depreciation is calcualted by the system is , 2,300 uptil aug 2009 which is correct.i.e

Depreciation for july 2008 to june 2009 is 20000*0.1=2000

Depreciation for the month of july 2009 is 20000-2000=18000*.1/12=150
Deprecition for the month of Aug 2009 is 18,000*.1/12= 150
-----
300
Now i run depreciation in SEP 2009 the depreciation was 166.6667 which is based on actual cost added in july 2008 .i.e 20000*.1/12=166.6667.Instead it should be 150 i.e 18000*.1/12=150

Why the system is calculating DEPRECIATION on actual cost instead NBV ?


Regards

Naveed Hasan