UIScrollView not zooming at all

I made a UIScrollView, added a UIImageView to as a subView, set the viewForZoomingInScrollView: method to return the subView, set the UIScrollView's delegate to self in my viewDidLoad, set my 开发者_运维技巧ViewController to be a UIScrollView delegate, set the maxZoom to 5.00 in IB, and I still am unable to scroll

I'm using the iPhone simulator, pressing the option key to get they grey circles then moving my mouse, and nothing's happening.

Any ideas what I'm missing? Cheers

Did you set the content size?