UIButton need clicks two times for firing its action

I have two round开发者_如何转开发 rect buttons. I have implemented its touch up inside action. It works fine but when my click second button just after clicking the first button, my first click has no effect. This is happening with both the buttons. I am actually trying to change background image of buttons on each click to get the effect of check box (checking/unchecking). Below is the code for for one of the buttons:

-(IBAction) checkButton2: (id) sender
{
    self.checkButton2 = sender;
    if ( isCheck == NO)
    {
        [self.checkButton2 setImage: [UIImage imageNamed:@"check.png"] forState:UIControlStateNormal];
        isCheck = YES;
    }
    else
    {
        [self.checkButton2 setImage:[UIImage imageNamed:@"uncheck.png"] forState:UIControlStateNormal];
        isCheck = NO;;
    }
}

This is solved. Actually I was using isCheck BOOL type variable for two actions(One is given above) for two buttons and both actions were setting this variable separately which shows deviation from expected behavior.