I had this working a little while ago (well the servers did sync on their own, I never tried forced sync). Now however no sync is happening, forced or otherwise.
I can not offer any help other than to show what my logs show in the hope someone else may have an answer or suggestion (assuming your problem is the same as mine)
On the master the ebox log shows a lot of lines like this
2009/11/13 15:30:05 WARN> Events.pm:526 EBox::Events::__ANON__ - model EBox::Events::Model::Watcher::LogFiltering cannot be instantiated
2009/11/13 15:30:40 DEBUG> slave-sync:74 main::__ANON__ - Trying to run method addUser with param naomi.maloda on slave eboxcomms failed
2009/11/13 15:31:14 DEBUG> slave-sync:74 main::__ANON__ - Trying to run method addUser with param todd.sprinkel on slave eboxcomms failed
2009/11/13 15:31:33 INFO> Manager.pm:97 EBox::Monitor::Measure::Manager::register - EBox::Monitor::Measure::Thermal is not enabled to collect data
2009/11/13 15:31:34 DEBUG> LogFiltering.pm:70 EBox::Events::Model::Watcher::LogFiltering::new - Missing argument: tableInfo
2009/11/13 15:31:34 WARN> Events.pm:526 EBox::Events::__ANON__ - model EBox::Events::Model::Watcher::LogFiltering cannot be instantiated
2009/11/13 15:31:47 DEBUG> slave-sync:74 main::__ANON__ - Trying to run method addUser with param mwanga.chibago on slave eboxcomms failed
2009/11/13 15:32:21 DEBUG> slave-sync:74 main::__ANON__ - Trying to run method addUser with param naomi.maloda on slave eboxcomms failed
2009/11/13 15:32:55 DEBUG> slave-sync:74 main::__ANON__ - Trying to run method addUser with param stanley.machichimi on slave eboxcomms failed
While on the slave I am seeing this in the ebox log
2009/11/13 15:31:57 DEBUG> UsersAndGroups.pm:2565 EBox::UsersAndGroups::waitSync - Master groups: 13
2009/11/13 15:31:57 DEBUG> UsersAndGroups.pm:2566 EBox::UsersAndGroups::waitSync - Replica groups: 13
2009/11/13 15:32:00 DEBUG> UsersAndGroups.pm:2563 EBox::UsersAndGroups::waitSync - Master users: 5
2009/11/13 15:32:00 DEBUG> UsersAndGroups.pm:2564 EBox::UsersAndGroups::waitSync - Replica users: 1
2009/11/13 15:32:00 DEBUG> UsersAndGroups.pm:2565 EBox::UsersAndGroups::waitSync - Master groups: 13
2009/11/13 15:32:00 DEBUG> UsersAndGroups.pm:2566 EBox::UsersAndGroups::waitSync - Replica groups: 13
2009/11/13 15:32:00 ERROR> UsersAndGroups.pm:2573 EBox::UsersAndGroups::waitSync - Replication failed
2009/11/13 15:32:04 DEBUG> UsersAndGroups.pm:2563 EBox::UsersAndGroups::waitSync - Master users: 5
2009/11/13 15:32:04 DEBUG> UsersAndGroups.pm:2564 EBox::UsersAndGroups::waitSync - Replica users: 1
2009/11/13 15:32:04 DEBUG> UsersAndGroups.pm:2565 EBox::UsersAndGroups::waitSync - Master groups: 13
2009/11/13 15:32:04 DEBUG> UsersAndGroups.pm:2566 EBox::UsersAndGroups::waitSync - Replica groups: 13
2009/11/13 15:32:08 DEBUG> UsersAndGroups.pm:2563 EBox::UsersAndGroups::waitSync - Master users: 5
2009/11/13 15:32:08 DEBUG> UsersAndGroups.pm:2564 EBox::UsersAndGroups::waitSync - Replica users: 1
2009/11/13 15:32:08 DEBUG> UsersAndGroups.pm:2565 EBox::UsersAndGroups::waitSync - Master groups: 13
2009/11/13 15:32:08 DEBUG> UsersAndGroups.pm:2566 EBox::UsersAndGroups::waitSync - Replica groups: 13