Fixed asset

I succeed to make calculation amortization to the 31/12/05 on a good acquired in 2005, with an ulterior movement of purchase to February 2006. Navision checks Last Acquisition Cost Date on the fixed asset and skips it. The cost of 2006 goes in budget 2006. The depreciation of the 2005 will be calculate in February 2006 (with posting date 31/12/05). What I can make? You have other ideas? Thanks to all