Export - only audio and titles appear

I am a new user. I downloaded the paid product yesterday. I want to make simple videos showing students how to do tasks for my classroom.

I did a video and when I export it, the titles and audio work - but there are no images or video. It shows a black screen only.

I already uploaded the project files from the timeline onto Google Drive and shared it. Here is the link.

Thanks for any help you can offer to a beginner. If you know how to fix this, could you explain what you did - so I can fix what I am doing?

Thanks in advance,

Download and install this version. Ignore any security warnings.

Your registration may not be accepted but the unlicensed release should still be good for export. If it balks, try the AVI format.

In a few days redownload the latest version, install and register it.

Please leave your files on the server for a week, if possible.