SonicWall SonicPoint AP not handing out DHCP addresses

AD controller is also DHCP server.
Network is all Brocade FastIron switches.
Two APs, both SonicPoints, hanging off of switches.

One AP works just fine.

The other AP shows the correct SSIDs, clients can authenticate, but getting a DHCP address fails.

If I roam from the good AP to the bad one, I keep my IP, but I can't actually reach the internet even though the connection appears to be good.

I've disabled LLDP on the APs' ports, ensured that their ports are on the same VLANs, set STP to fast-enable... no dice.

I'm just a Cisco babby, so I'm probably just missing some setting specific to Brocade and SonicWall products.