Dell PowerConnect n2000 Freeradius issue

Hi,

I'm a new one in PowerConnect community. I discover this environement and i'm front of an issue.

I have a FreeRadius ( base on Pfsense) and my n2048 and I try to make 802.1x authentification.

I have a Windows 7 workstation as test client.

When I try to authenticate I have this message in Switching/dot1x authentication/Monitoring mode/port access control history :

Dot1x : Radius authentication Comm Failure

And few seconds later :

Dot1x Authentication due to Guest Vlan Timer Expiry ( and the port is tagged on vlan 2 as expected in this case)

But why in first step I have a Comm Failure, is there somewhere a log file to find what's happened ?

Thank you for your help.