1. The possible reason of the error "Can’t activate RAPI session." is that Mac firewall blocks the connection or PDA firewall blocks driver installation. On Mac, try this: System Preferences -> Security/Sharing (Internet and Network)-> Firewall -> Allow All Incoming Connections.
2. Make sure that Activ Sync is started on your mobile device:
Start > Program > Activ Sync > Menu > Connections > check box "Sync all PCs using this connection" > drop down list USB
3. Also go to your Mac’s Network settings and select Winmobile network adapter. Set the following configuration:
ip address: 169.254.2.2
Apply and connect your mobile device.
4. The problem may also occur if another synchronization software (the previous version of SyncMate or other software) wasn’t properly uninstalled so an invisible usb driver is still present in the system. It doesn’t allow to connect when you install SyncMate after Missing Sync or another version of SyncMate.
– To uninstall Missing Sync run its uninstaller and then manually remove folder "/Library/Application Support/Missing Sync for Windows Mobile".
– Check this article on how to uninstall SyncMate: /wiki/knowledge-base/syncmate/uninstall-syncmate.html