GSS 3.1 : WinPE AF "black screen"

Hello, i'm stuck on a weird problem.

My gss 3.1 installation is brand new and i was testing automation folder with one virtual machine, this virtual machine is a windows 7 pro x64 computer. I have made a configuration for WinPE 3.1 env then created an automation partition installer later deployed on the window 7 without an issue.

For testing purpose i launched an image creation task, the virtual machine is rebooting just fine but when enterring in the winpe env i get a black screen with only the mouse available :/

I get the same result on a physical machine via a pxe boot.

What i am missing on things to do ?

Thx in advance.