MU2 Update fails on 2 server of 7

Hy everybody!

I have a big problem, I have established the MU2 on my master zen server and patch the MU2 with the lastest updates of the MU2 with this commands:

zman sui ZENworks_11.2.1_MonthlyUpdate2.zip
zman supf "Monthly Update 2 for ZENworks 11 SP2 (11.2.1)" ZCM_11.2.1_20120917_776384.zip
zman supf "Monthly Update 2 for ZENworks 11 SP2 (11.2.1)" ZCM_11.2.1_20121022_782534.zip
zman surp "Monthly Update 2 for ZENworks 11 SP2 (11.2.1)"

after this I wait until all ZenworksServer (they are all primary server) have replicated the MU2.

Now my problem I make a "zac ref" and the update starts - on 5 server of 7 the updates finished without any problem.

On the other 2 I get this message from the system-update.log:

DEBUG;Running Pre-Install Commands;;
DEBUG;Getting content for PRE_INSTALL steps of update;;
DEBUG;Got 5 pre install commands;;
DEBUG;Running command: ${content.0.path};/opt/novell/zenworks/bin/zenupdater;;
DEBUG;Running command: /bin/chown;;
DEBUG;Running command: /bin/chmod;;
DEBUG;Running command: /bin/sync;;
DEBUG;Running command: ${content.0.path};${ZENWORKS_HOME}/zmd/java/lib/systemupdate/ZENUpdater.jar;;
DEBUG;One or more pre install actions failed. The update will not be processed (Monthly Update 2 for ZENworks 11 SP2 (11.2.1));;


all required updates are installed on the server:

Monthly Update 1 for ZENworks 11 SP2 (11.2.1) Update Completed
Update for ZENworks 11 SP2 (11.2.1) Update Completed
Monthly Update 2 for ZENworks 11 (SP2) Update Completed
Monthly Update 1 for ZENworks 11 (SP2) Update Completed

I have checked the directory: /opt/novell/zenworks/zmd/java/lib/systemupdate/ -> there is no ZENUpdater.jar
same in the directory/opt/novell/zenworks/bin/ -> there is no zenupdater

Have someone an idea why this is happen?

big thx for your help!