I'm a steam user, I have both installed, but i think OA's runing as a standalone and I'm using the stkr_britmtp_oacfg PBO
edit: Managed to fix it, I had another Cfg Pbo in there "STKR_BritMTPcfg" I removed that and it works fine.
Cheers for a great British Mod Stalker, keep up the awesome work, I've always enjoyed the high quality of any and all of your units.