You should log a PMR first of all.
Have you enabled trace in the client? Take a look at
http://www.ibm.com/support/knowledgecenter/SSKTXQ_9.0.0/admin/trouble/trbl_client_log_trace.html and specifically the following trace
Meetings:
General meeting issues:
com.ibm.rtc.meetings.level=FINER
com.ibm.rtc.spaces.level=FINER
com.ibm.collaboration.realtime.appshare.level=FINER
com.ibm.rtccore.level=FINER
com.ibm.sharedmaps.level=FINER
Calendar integration issues:
com.ibm.rtc.meetings.servers.level=FINEST
com.ibm.rtc.meetings.shelf.level=FINEST
com.ibm.rtc.meetings.shelf.ui.level=FINEST
com.ibm.rtc.meetings.util.level=FINEST
com.ibm.collaboration.realtime.calendar.level=FINER
com.ibm.collaboration.realtime.calendar.notes.level=FINEST
Connectivity issues:
com.ibm.rtccore.level=FINEST
com.ibm.rtc.spaces.level=FINER
Screen sharing issues:
com.ibm.rtc.meetings.appshare.level=FINER
com.ibm.collaboration.realtime.appshare.level=FINER
Document sharing/conversion issues:
com.ibm.rtc.meetings.documents.level=FINER
com.ibm.rtc.meetings.appkit.image.level=FINER
com.ibm.workplace.converter.level=FINER
Also, how many bits is your SSL certificates assuming you're connecting to it over HTTPS? If you have a certificate over 2048 bits then you would need to deploy the unlimited policy jars to each client.
Enable some trace and take a look at what is spat out