Can't get camera permissions dialog to show up

I'm developing a Flash app that allows the user to select photos from their computer, Facebook, or use their webcam. When they click to use their webcam the camera permissions dialog pops up as expected. If they deny permission to use the camera, I send them back to the selection screen.

That said, I want to allow them use select webcam a second time in case for some reason they misunderstood the permission request or changed their mind. When I call the attachCamera method a second time I expect the dialog to pop up again however it doesn't. Any idea if there's a way to pop it up a second time?

Thanks!