New Unit Problem

I've been wanting to crate a byzantine musketter unit for awhile now, finally got around to it yesterday. Went trough the process of giving byzantine guard archers muskets from cossack musketeers, then adding the resulting unit to the game. But I keep getting a crash, and I have no idea why. The game starts, the unit shows up in custom battle selection screen, but when I try and strart a battle with it, the game crashes, due to an unknown error, according to the log. Can anyone please tell me what could be causing this? Is it a problem in thext files or the model itself?