Make sure the Slave Clock cable is connected to the 1X/256X port on the MTP AV on one end, and the Slave Clock In port of the audio interface on the other. Also make sure the MTP AV clock out is set to deliver Slave Clock to Pro Tools, not Word Clock:Scroll the WINDOW pot until you seeSYNC 00:00:00:00INTERNAL 44100Then scroll the CURSOR pot until you seeWORD CLOCK OUT<--44.1K 1X-->Keep scrolling the CURSOR pot until 1X is flashing, then scroll the VALUE pot until it says DIGI-->. If it already said DIGI, then this is not the problem and you should begin to suspect a hardware failure on the audio interface or the MTP AV, or possibly a failing BNC cable.