Presenting a modal view controller immediately after dismissing another

I'm dismissing a modal view controller and then immediately presenting another one, but the latter never happens. Here's the code:

 [self dismissModalViewControllerAnimated:YES];

 UIImagePickerController *picker = [[UIImagePickerController alloc] init];
 picker.delegate = self;
 picker.sourceType = UIImagePickerControllerSourceTypeSavedPhotosAlbum;
 [self presentModalViewController:picker animated:YES];

The first modal VC slides down, but the new picker never comes up. Any idea as to what's going on?