Group Asset Isssue -URGENT

I have configured the Group Assets for tax depreciation.For each asset we have to assigne Group asset while creating asset master.So,,,,the issue is...when group asset created we gave the capitalized date as 01/04/2008.but we created normal asset on 01/05/2008. the problem is Depreciation is calculating from 01/04/2008 even though the asset is capitalized on 01/05/2008.How to overcome this issue?

Please give me suggestions

Should separate group assets be created for each normal asset with different capitalization dates?

Thanks