help! DBM AB problem

I'm trying to create a file for the Wars of the Roses English DBM
army list in Army Builder. I follow what I thought was the race-
prefix scheme for DBM files and come up with zc as the race prefix,
but when I set up the skelton of the file and try to load it onto AB,
it says there's a race-prefix conflict with zc.

I don't see (just based on the file names) any "zc" prefixed lists.
What gives? Why am I getting this error?

Thanks for any words of advice.

Jan