asterisk users - Apr 2006 - Registering to H.323 Cisco gatekeeper

I'm having trouble registering my asterisk to a cisco gatekeeper. I do
not have control over the gatekeeper, and I know that it has user info
defined in an LDAP. I have a user name and a password that I can use,
but I can't seem to get Asterisk to register on the gatekeeper.

I can't find exactly how I'm supposed to define the gatekeeper in the
h323.conf file. This is the response I get in Asterisk:

  == Registered channel type 'H323' (The NuFone Network's Open H.323
Channel Driver)
  == H.323 listener started
Error registering with gatekeeper "<ip address>".
Apr 26 12:37:59 ERROR[10237]: chan_h323.c:2374 load_module: Gatekeeper
registration failed.

The box is supposed to be a SIP/H.323 converter.
-- 
Nils-Anders

My system worked fine all day. Then about an hour ago the following 
happened.

1) When someone dials in to us, their phone just rings our number and the 
digital receptionist never picks up.
Any ideas what can cause this. I did not do any upgrades, configurations or 
reboots.

What direction should I be looking at for a solution to this problem?

Thanks!!