Aerial not showing up in background when making pdf

I usually work with very large .tif files, for some reason when I make a pdf of a dwg with the aerial attached to the dwg, the only thing that comes out is the vector. It use to work, then all of a sudden it doesn't. The IT dept. upped my virtual memory, but that didn't seem to help. I'm using Autocad Map 3D 2010.

Has anybody ever had this problem?

Is it is on a layer set to print?

Yes, the layer is set to print. The odd thing is yesterday when I fooled around with it, I windowed a small portion of the dwg to print and it did. As I made my window larger, the aerial would not show up on the pdf file. I put a call into Autodesk and he is trying to help me figure this out. It's just the weirdest thing. Thanks for your reply.