Lost frames

Having problems with a client.  He sends me AVID output to H.264.  Generally 29.97 Drop.  1080.

I stick it in After Effects.  Do my graphics work, output and send back as H.264.

When he imports into Avid.  The first frame is black and the pie      ce is short by at least 2-3 frames at the end.

I am creating my comp exactly to the length of the footage he gives me.  Exactly.    Matching frame rates exactly.

This happens on every piece I send back to him.  I open in Quicktime and the first frame is fine.  But on the AVID first frame is black.

Any thoughts?

TAK