Have you applied the patches for the basic RTW game through 1.2? IIRC you have to put those on before you apply BI, and it adds the 1.3 patch. But it's been a couple years since I did that so maybe I'm not remembering it right.

You do have RTW installed first right? BI is only an expansion for RTW, not a stand-alone game. Can't tell from your post whether you're aware of that.