Error in multible fields in append querie

Hi there, I have this append query which has a lot of references to other tables and queries. I use the DB to depriciate our companycars. after running depriciations for november I discovered that the DB for the first time "forgot some cars". I found out that for those cars missing there were an '#error' in some fields in the append querry.. Does any one have the sligtes clue what this can be.

Regards
MP