FreeNX "nxagent -query" broken

When trying to connect to a KDM process using XDMCP as described here by Fabian, the !M logo briefly appears but then the display stays dark indefinitely:

http://mail.kde.org/pipermail/freenx-knx/2006-March/003106.html

This still seems to have worked a few moths ago, but no more with nxagent 3.3.0-3-6-0freenxteam9 on Ubuntu Intrepid x86 (freenx-server 0.7.3+svn612-0freenxteam10):

http://lists.kde.org/?l=freenx-knx&m=120107963106878&w=2

Here's the nxagent -query 192.168.10.10 output after failure (X -query 192.168.10.10 works without problems, KDM greeter displayed):

Couldn't open RGB_DB '/usr/X11R6/lib/X11/rgb'

NXAGENT - Version 3.3.0

Copyright (C) 2001, 2007 NoMachine.
See http://www.nomachine.com/ for more information.

Info: Agent running with pid '4350'.
Session: Starting session at 'Thu Dec 4 09:53:16 2008'.
nxagentSetDeferLevel: Assuming defer level [0] with timeout of [200] ms.
nxagentSetDeferLevel: Assuming tile width [4096].
nxagentSetDeferLevel: Assuming tile height [4096].
nxagentSetCoalescence: Using coalescence timeout of [0] ms.
nxagentPostProcessArgs: Disabling dispatch of exception at server reset.
Info: Using alpha channel in render extension.
Info: Using local device configuration changes.
error opening security policy file /usr/X11R6/lib/X11/xserver/SecurityPolicy
nxagentKeyboardProc: Called for [DEVICE_INIT].
nxagentKeyboardProc: Set repeat delay to [4294967295] interval to [4294967295].
nxagentCheckXkbBaseDirectory: Before calling _NXGetXkbBasePath.
nxagentCheckXkbBaseDirectory: XkbBaseDirectory varible [/usr/X11R6/lib/X11/xkb].
nxagentCheckXkbBaseDirectory: After calling _NXGetXkbBasePath.
nxagentCheckXkbBaseDirectory: XkbBaseDirectory varible [/usr/share/X11/xkb].
nxagentKeyboardProc: Using XKB extension.
nxagentXkbGetRules: XkbBaseDirectory [/usr/share/X11/xkb].
nxagentKeyboardProc: Using default keyboard: model [pc102] layout [us].
nxagentKeyboardProc: XkbInitialMap [NULL]
nxagentKeyboardProc: Init XKB extension.
nxagentKeyboardProc: Remote: [evdev,pc105,de,nodeadkeys,lv3:ralt_switch].
nxagentKeyboardProc: nxagentXkbConfigFilePath [/etc/nxagent/nxagent.keyboard].
nxagentKeyboardProc: Going to parse config file.
nxagentKeyboardProc: Going to set rules and init device.
nxagentChangeKeyboardControl: Repeat delay was [65535] interval was [65535].
nxagentChangeKeyboardControl: Repeat delay is now [65535] interval is now [65535].
nxagentChangeKeyboardControl: WARNING! Propagating changes to keyboard settings.
nxagentKeyboardProc: Called for [DEVICE_ON].
Session: Session started at 'Thu Dec 4 09:53:16 2008'.
nxagentInitXkbWrapper: Called.
nxagentInitXkbWrapper: base [138] eventBase [86] errorBase [148].
nxagentEnableXkbExtension: Called.
nxagentEnableXkbExtension: Nothing to be done for ProcXkbDispatch.
nxagentEnableXkbExtension: Nothing to be done for SProcXkbDispatch.
nxagentWakeupHandler: WARNING! The XDM session seems to be unable to start after [20497] ms.
Error: Aborting session with 'XDMCP fatal error: Session failed Session 261824010 failed for display 192.168.10.9:1: cannot open display'.
Session: Aborting session at 'Thu Dec 4 09:54:32 2008'.
Session: Session aborted at 'Thu Dec 4 09:54:32 2008'.

For comparison, the output from Nomachine nxagent 3.3.0 (which displays the KDM login greeter straight away without problem):

$ /usr/NX/bin/nxagent -query 192.168.10.10 :1

NXAGENT - Version 3.3.0

Copyright (C) 2001, 2007 NoMachine.
See http://www.nomachine.com/ for more information.

Info: Agent running with pid '4769'.
Session: Starting session at 'Thu Dec 4 09:47:53 2008'.
Info: Using alpha channel in render extension.
Info: Using local device configuration changes.
error opening security policy file /usr/X11R6/lib/X11/xserver/SecurityPolicy
Session: Session started at 'Thu Dec 4 09:47:53 2008'.
Session: Terminating session at 'Thu Dec 4 09:48:11 2008'.
Session: Session terminated at 'Thu Dec 4 09:48:11 2008'.