IIS 8 wordpress installation not working

Hello,
i am trying to install wp for IIS 8 (win 2012 R2 on a VM).
During installation i select not default web site.
The installation completed but the WP installer was not launched.
It seems that php is not working correctly.

When browsing the webpage, i get all files and dir listed.
but clicking on any .php file i get error 500.

Module FastCgiModule
Notification ExecuteRequestHandler
Handler PHP55_via_FastCGI
Error Code 0x80070003

The CGI feature is enabled.
After some research, it is may related to permissions.
But for my pyhsical folder i added IIS_USR to have read and execute
rights.

Where should i look to fix this ?
Thank you