Purchase of Assets during the Period

Hi Experts,

Recently I am facing a typical problem.I am new in SAP.

We had purchased one asset in the month of April amounting to Rs.65,000/- dated 23.04.2009.When we run AFAB for the month of April-2009 we noticed that system is calculating depreciation on the said asset for the full month not for 8days(i.e 23.04.2009 to 30.04.2009).

Anybody, please throw some light in this case.I am open to change the customisation.

Thanks & Regards

CONSAPFI