Tethering iPhone 4S with Aperture 3 Project

is it possible to use my iPhone 4S as a tethered camera? I used to be able to do it in A2.

I connect the iPhone via USB, select a test project and then select File/Tether/Start Session. Then I click "Start Session"

It opens the Tether HUD and recogizes my iPhone as the Camera, but the Capture button is greyed out.

Tried opening the camera app on the iPhone and reconnecting, nothing. Am I missing something?

Thank you in advance.