Diana,
I ran into this about a year ago so I'm a little fuzzy on the fix. I think it had to do with the GL account at the Vendor Division overriding the GL account defined for the bank account. We cleared the cash account at the division level blank and the system started using the bank account to get the coding.
Try this at your site first. As I said, I'm a little fuzzy. (No bald joke!)
Cheers.