Error on connection to Mission planner on Mac 10.9.5

Hi, I can’t get my brand new arduo 2.8 to connect to my macbook. I’ve uninstalled and re installed. I’ve downloaded a FTDIUSBSerial.pkg and installed but it just won’t open. I get the message
Failed to open an RFCOMM serial channel.
Check if authentication needs to be enabled in your device.
any help would be most welcome please.