Cakewalk won't generate its own timecode, so you need to have the BRC generate timecode. Make sure in Options-Midi that the port you have going to your BRC is activated. Go to Options-Project-Clock, change the Source to SMPTE/MTC. Then go to Midi Out, turn on Transmit MMC. This will tell the BRC to start generating timecode, and sync Cakewalk to the incoming timecode MTC.