Manage Communications for Linux not working

[csmathon]

Hi Everyone,
 
I just installed HP SIM 6.3 in my environment. Now I'm trying to add some Linux machine (red hat 4) in it.
The discovery works fine but then when I go to the Manage Communications menu, it says:
 
"The HP SIM Central Management Server may not be on the managed system(s)' SNMP trap destination list, so no events will be received from the system(s)."
 
I did run the Quick Repair. After running it, the error disappears, until I click on "update" in the "Manage Communications" menu. (see screenshot for a visual ;) ) 

Any logs I can check or activate to troubleshoot this?

Regards
Christophe