Hi Marco,
You may need restart IQCockpit service.
Make sure the cockpit user connected to IQ system fits the required privileges:
3.1.2 Multiplex Privilege Summary
http://help.sap.com/Download/Multimedia/zip-iq1608/iqcockpit.pdf
Also check related messages in Cockpit log files (agent.log, gateway.log, repository.log) located in $SYBASE/COCKPIT-4/log
Regards,
Tayeb.