I was doing this today and had similar issues:
what i did was made sure my frames were padded to four digits e.g. 0100 and then turn on use image sequence. Then there is a box undr that that says "frame number". Click the box next to that and it should add the expression:
frameExtension=frame
If it doesn't do that then it will go black. Make ure your padding is correct I think that may cause you problems
Alan
Technical Director - Framestore
Currently working on: Your Highness
IMDB