Windows 2000 Server using FreeRadius

I am trying to get a Windows 2000 server (stand alone NOT running AD) to use FreeRadius instead of IAS. I have set the FreeRadius server in Windows Routing and Remote Access as the authentication provider, and set the secret password the same on both servers. When trying to authenticate via VPN, the W2K server passes it to the FreeRadius server, but it ends up no authenticating. I checked the radius.log file, and it indicates the secret is not correct even though they are set the same. If I change W2K to use IAS it works, and if I use a Cisco router instead of W2K with FreeRadius it works!