From your description, I believe your issue is in mocha, go to the frame number that you created your clean plate on. Then use the align frame function to make your surface a full frame.
Than in AE go to the first frame of comp and past the exported mocha Corner Pin data.
This should work, so if you are following these steps I think there is something missing.
Best,
Ross
Ross Shain
Imagineer Systems
http://www.imagineersystems.com