imovie ios not exporting

So I used this app for a tradeshow last year to do on the floor videos, edit and upload. I am doing another next week. I was doing a test of the app and I cannot get it to export a video whatsoever. I have tried exporting directly to the camera roll and to yourtube. It is only a 20 sec clip nothing huge. I have tried on WIFI and on 4G. I am leaving in two days and I need this to work. help me!