Error: You cant post to asset in campany code XXXX in fiscal year 2007
occurs at T code ABT1n (transfer of asset)
Firstly check FI period is open or not
You may have closed Asset year 2006 using T code AJAB.
if it is already closed and you want to post entries, then undo asset closing using t code OAAR(but this has to be tested in test client)