NPS: Event 6274 - Network Policy Server discarded the request for a user

I'm trying to setup radius for our wireless network.
Every time i try to connect a client to the network i get the error below.
It seems to go wrong when the identity gets validated.
I've search the net but haven't found any usefull info about this event.
Does anyone have an idea?

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Network Policy Server discarded the request for a user.

Contact the Network Policy Server administrator for more information.

User:
Security ID: S-1-5-21-1766481294-3300188777-3290954597-2797
Account Name: company\name
Account Domain: company
Fully Qualified Account Name: company\name

Client Machine:
Security ID: S-1-0-0
Account Name: -
Fully Qualified Account Name: -
OS-Version: -
Called Station Identifier: 00-1B-11-1A-D8-10:Company
Calling Station Identifier: 00-16-6F-71-A0-7F

NAS:
NAS IPv4 Address: 192.168.254.22
NAS IPv6 Address: -
NAS Identifier: D-Link Access Point
NAS Port-Type: Wireless - IEEE 802.11
NAS Port: 1

RADIUS Client:
Client Friendly Name: dlink dwl3200ap
Client IP Address: 192.168.254.22

Authentication Details:
Proxy Policy Name: Secure Wireless Connections
Network Policy Name: Secure Wireless Connections
Authentication Provider: Windows
Authentication Server: radiusserver.Company.local
Authentication Type: EAP
EAP Type: -
Account Session Identifier: -
Reason Code: 1
Reason: An internal error occurred. Check the system event log for additional information.