Facing error for current month additions load into Oracle FA

We are in 12.1.3 and our fiscal year is Oct to Sep. We are migrating to FA and have setup the first period as Jan-21 . We are planning to load legacy asset balances as on 31-Jan (with depreciate flag as N) and once reconciled we want to start depreciattion from Feb-21 by setting depreciation to Y. There were few assets that were acquired in Jan-21 in the legacy system and the asset listing included their cost, YTD depn (Jan-21) and reserve (same as ytd) as on 31-Jan. The web adi load worked fine but during Mass Additions Post we