Women Mental Block on Back Tuck

[NaomiN]

I'm an Xcel silver gymnast trying to get my back tuck. I am really good at drills and have been working on drills and jumps for the past few weeks. Although, when I actually get up to do it I feel like I can't do it and end up jumping backwards and landing on my feet or giving up halfway and just falling on my back. I try to do it off of a block onto a super squishy mat with a very heavy spot from my coach yet I still feel like I have forgotten how to do it and can't physically go through the motion. I have tried multiple techniques but nothing has worked. I have my front tuck and never get mental blocks on that, but my back tuck just isn't working. I know I could get around this and not do back tuck for Gold next year but I want to challenge myself and I also need it for high school cheer. Please help!