asterisk users - Sep 2004 - H323 - Control Protocol Error (Master slave Determination)

Hi there ! 

I searched the whole web to find some helping information about H323
Control Protocol, but there is no way to find that information.
We compiled and installed asterisk_0.9.0 + pwlib 1.5.2 + openh323_1.12.2
+ 'asterisk-oh323_1.5 channel driver + wrapper' and configured the
dialplan for using our H323 Endpoints which are ip200 Innovaphones.
Besides, we also use Gnomemeeting but don't care it's not the problem, I
think ! 


The whole endpoints are registered on an ip400 Gatekeeper which routes
every call to asterisk, and asterisk processes the Dialplan and sends
the call back to the ip400 and to the correct Endpoint.

With this configuration the Endpoints can dial each other above the
Gatekeeper and Dial Plan. ;-) well pretty fine - the only damped thing
is every call loses connection after 30 sec because of a a H323 control
protocol error .  




this is the asterisk output while phoneing :
###############################################################################

*CLI>    
    -- Executing Dial("OH323/R1",
"OH323/4020@10.88.250.250:1720|15") in
new stack
    -- Called 4020@10.88.250.250:1720
    -- OH323/L13468 answered OH323/R1

>>>>>>        *** [ip$x.x.x.x:2507/1] H.323 CONTROL PROTOCOL
ERROR
(Capability Exchange)
>>>>>>        *** [ip$x.x.x.x:2507/1] H.323 CONTROL PROTOCOL
ERROR
(Master-Slave Determination)




*CLI> Sep  2 13:57:15 ERROR[294931]: chan_oh323.c:1212 oh323_hangup:
OH323/L13468: Failed to hangup channel (timeout).
    -- Hungup 'OH323/L13468'
  == Spawn extension (buero, 3020, 1) exited non-zero on 'OH323/R1'
    -- Hungup 'OH323/R1'

*CLI> 
###############################################################################


I hope you can help me and the whole asterisk community to solve this
problem 

Hopefully, and waiting for response

greets 

alex