Welcome to the forum.
Unfortunately, you have posted to the Tips & Tricks sub-forum. This is basically a repository for articles on how to do things. Most users will not see your post here, but Steve Grisetti, our MOD, will probably soon move your post out to the main PrE forum, where others can see and comment on it. Do not be surprised if it moves on you.
Now, please tell us about your Assets, your source Clips. The more detail, the better. There can be many reasons why the Video will not display. We need as much info, as is possible to determine why it's happening to you.
Good luck, and we'll be looking for those details - they can be very important. Also, please tell us which Project Preset you used, when you did Project New.