iMovie won't let me share my project.

I have a project I've been working on for quite a long time and it's really frustrating not being able to share it--not anywhere. I can't even save it to my desktop, or post it to YouTube directly from iMovie.

The quality of it is just fine, the audio is doing okay, nothing like that is the problem. Just the sharing.

The footage was recorded using a Sony A65 SLT, and I have the latest version of iMovie installed on my Macbook Air (just in case that makes any difference).

Anyone have any advice or tips for me?