scrollViewDidScroll never called

Question

I have a Scrollview within View. I want to use the function scrollViewDidScroll to check and update the arrows (left right).

- (void)scrollViewDidScroll:(UIScrollView *)scrollView {

    NSLog(@"Did scroll");
    [self updateButtons];
}

It seems scrollViewDidScroll won't be called when I scroll left or right. I searched everything but didn't found a solution.

Hope someone has a solution.