Weird, it should be working just fine. I even just tested it with a save I had. o.o You're sure that you're not accidentally going too far each time? Or going the wrong way?

When you get onto the safe, TAP to the right to 5 and you should hear a distinct click telling you it was the right input. Then tap to the left until it goes past 0 and around to 40 for another click, and then back right again to the 7. Keep listening for the clicks and take it slowly and you'll be fine.

ok ill try it thank you