Are you seeing anything in the radius server logs?
What type of radius server do you have ?
Did this work before?
Is this issue with only 1 ap ?
"Satisfaction does not come from knowing the solution, it comes from knowing why." - Rosalind Franklin
Just to add my 2 cents, you have the SSID setup or wpa, but your clients are setup or wpa2? This will not work if that is how you have it setup. I'm also guessing you have defined the radius server on the AP and have added the ap as a AAA client on the radius server with the same shared secret? In your windows 7, you have the client setup for wpa-enterprise?