802.1x PEAP

I'm trying to use 802.1x with PEAP for our wireless network. In order to use
that we have a RADIUS server (Windows 2003 IAS), AD in native mode, but no CA
deployed. Is this the first mistake?

I have followed the "Obtaining and Installing a VeriSign WLAN Server
Certificate for PEAP-MS-CHAP v2 Wireless Authentication" guide from
Microsoft, and it doesn't mention the need for a CA.

So following the guide, I've installed the VeriSign WLAN server certificate
on the IAS server, in the Local Computer certificate store. I've verified the
installation. On the client, I have setup for 802.1x PEAP, ticked the
validate server certificate and selected the Trusted Certificate Authority
Root as VeriSign Class 3 Primary CA -expire 8/1/2028, as stated in the guide
mentioned above.

I'm unable to connect to the network. I am getting the following errors in
the event log on the IAS server.

Event Type: Error
Event Source: IAS
Event Category: None
Event ID: 20168
Description:
Could not retrieve the Remote Access Server's certificate due to the
following error: The credentials supplied to the package were not recognized

Event Type: Error
Event Source: IAS
Event Category: None
Event ID: 3
Description:
Access request for user domain\user was discarded.
Reason-Code = 1
Reason = An internal error occurred.

Can someone please please advise me on where I'm going wrong?

Thank you