[UIImageView startAnimating] Problem

Hello,

I have one problem in UIImageView Animation.

I initialize UIImageView in "initWithFrame" event. Assign array of images. Now i want to start animation when i tap one button.So,
In button tap i wrote [UIImageView startAnimating].

Problem is First time animation not works properly. From the second time it works perfect.

If I wrote [UIImageView startAnimating] when I add imageview to UIView it works. But I don't want to start it in "initWithFrame" event.

This problem comes in iPod iOS 3.0 not in iOS 4.0.

Thanks in advance.