Adding an effect gives me a red cross.

Good Morning everybody. I have a little problem, and when i put on some effects from the video effects folder (effects), a small red cross appaears in the previewrs, and when i export the video it appears too. I've searched for it in the internet and alk i found was that this thing can happen with the demo version, but i have no demo!!! I have the student plan with all of the programs!

Can you help please? Thank you.

Lucía