ARRGG jump PROBLEM

iWin

Some of you might know my game Mobile Snail. Its a jumping game so if it doesnt jump you cant play the game. Well i sent it to apple and its in the app store. My friend bought it and it doesnt jump at all.!!..it makes no sense because it worked fine on the web..IDK whats wrong

my rule is:

This is for gravity;
Accelerate down at all times (speed=300)

This is to jump;
Accelerate up when attribute jump is true
(attribute jump becomes true when you touch the screen)

Does anyone have a solution..AHH..thanks

iWin

OMG..i tried change velocity when jumping and it worked fine but of course it doesnt work on the viewer, which means it doesnt work on the store...?????????