Playback shows Black screen in Rush

I've just purchased Rush and unfortunetaly, its already getting on my.........

I've managed to import my video clips onto the timeline, the audio is working fine and, in sync with the video.  The problem is as the video plays, nothing is showing inthe preview window.  Just a black screen.

I've tried to clear my "Cache"history, restarted my pc but still nothing.  Any ideas please.  I am using windows 10 on a desktop.

Please help as i'm about to cancel my susbscrition.

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