iphone shake error

Question

Right now I have this-

- (void)motionEnded:(UIEventSubtype)motion withEvent:(UIEvent *)event
{
 if (event.type == UIEventSubtypeMotionShake) {
  int  text = rand() % 12;

  switch (text) {
   case 0:
    textview.text = @"blah." ;
    break;

For some reason, the text has to be selected for it to work. If you just shake it, nothing will happen.