Summon problems

The game is amazing but when I press the summon button for a multi or single it kicks me out of the app, and so I check my character list to see their are no new characters and all of the dragon stone I wasted on the banner are gone. Please fix this issue so this wont happen again, and I paid for these stones so it was really disheartening to lose that.

Alejandr077 about DRAGON BALL Z DOKKAN BATTLE, v3.0.1