For debugging the NetMeeting directory kit Brent Baccala suggests using
ethereal (http://ethereal.zing.org/)
to do a packet trace. It's LDAP support is quite good. There
is also a trace file option in the Perl script "netmeeting.perl"
that can be uncommented.
You might also try running the slapds with debugging turned on
(-d 768 is a good start), but their messages are rather confusing.
For debugging H.323, try using the "-t" and "-o" options, supported
by all the OpenH323 client programs.