Missing files when combine tiff files into video file

I am using a CS5 Suite and the After effects in the suite. I tried to combine tiff files into video file by loading it in powerpoint then rendering in to Quick time Pro. But as I was playing my output, there were 2-4 files that were skipped. I tried doing it again and this time, other files, different form the ones previously skipped in my first output was the ones that did not appear. Do you think there was something I missed while making this?