I am trying my first project. I have a number of video clips that I don't want on the same video line. I want them on different tracks (which they are) and have them all line up at the desired spot and time to the seperate Audio track. When I hit play there is only a black screen. I can see the time line moving and hear the audio track but dont' see any of the video tracks. They are not hidden, they just don't show up so I can't play them to line up against the audio track. How do I fix this? This is maddening!