Real-Time battles don't work in 1.5 when they do in 1.6

[alpaca]

Well, as the topic says.
I'm currently trying to get Chivalry playable for both 1.5 RTW and 1.6 BI - and the campaign map runs fine in both.
But when I try to start a battle in the 1.5 exe, the game CTDs on load or, in the case of custom battles, kicks me back to the custom battle faction selection screen.
The really weird thing about this is that the exact same custom battles work perfectly in the BI exe...

So, does anybody have any ideas what might cause this?
I don't have any swimming or hording units in edu btw.

[webbird]

Look at the battles coordinates, do they fit into your custom campaign map??? Try to use the battle editor, if you have made a map for the editor too, and check the locations there.

[Epistolary Richard]

As alpaca says, webbird, these are the exact same battles that work through the BI.exe - if there were incorrect coordinates then they wouldn't function in either.

[alpaca]

Ah sorry, I forgot to mention it:
Adherbal had already encountered this and told me how to solve it in this thread at the .org http://forums.totalwar.org/vb/showthread.php?t=64383