Gif-animation doesn't move

It seems I’m doing something fundamentally wrong exporting my animation as a gif.:

While exporting, the process-bar and preview seem to be alright (the animation is playing) but when I open the generated gif-file, all the animated elements are gone. When I open it in Mac’s Preview there are a lot of identical pages/frames always with the same missing elements that are supposed to be animated. :confused:

I tried to export a video and it worked.

What could be my problem?
I’m working with one main time axis and I’m not a very experienced Hype-user. So I’m sorry if I missed something substantial…

Thank you!