Does IAS work with Nortel VPN?

Just a quick shake down. I recently upgraded my NT 4.0
network to 2K3 AD. I took my old PDC(named "Apps") and
installed 2K3 and made it the new head of the 2K3 domain.
I brought in my spiffy new Dell servers, DC promo, move
the roles, and demoted Apps. So now here's the issue I'm
running into.

Apps runs Steel Belted Radius to authenticate our Nortel
Contivity 1500 VPN box. I have installed IAS on one of my
new Dell servers, but so far Nortel is not authenticating
through IAS. I have registered IAS with AD and seemingly
set up all the group and settings properly. But still the
client just spins when the VPN is pointed to the new IAS
Dell box.

Are there any tricks to get this to work? If anyone has
seen this or has any advice or suggestion it would be
greatly appreciated.

Thanks,
Mike