dismissViewController not working 4

This should be very straightforward, however I cannot figure it out which is extremely frustrating.

I have 2 view controllers, each embedded in a navigation controller, and on the 2nd VC I have a button which when pressed should dismiss/pop this view and essentially go back. I have tried both of these and neither works: [self dismissViewControllerAnimated:YES completion:nil]; [self.navigationController popViewControllerAnimated:YES];

Help please?