This error is due to one of two things:A) MIDI communication between the MIDI Interface and the ADAT Interface is compromised.B) The sync cables on the ADAT are not communicating to the ADAT Interface reliably.Please check the following:- Confirm cable connections and routing.- Confirm that the "4/8" switch on the ADAT I/O is in 8ch mode (in).- If using a Studio 3, verify the correct MIDI output is being used (the Studio 3 can be set to 1x6 or 2x3).- If using OMS or Free MIDI, confirm that the ADAT I/O is configured as a MIDI Device (Run OMS setup or Free MIDI Configuration). Also, enabling "send and receive MTC" is not necessary.- If using a MIDI Time Piece II, try resetting the interface with its "reset" procedure [done via the front panel]. This will return the MIDI interface to its original speed and setup. This may help the troubleshooting process- Confirm which Serial ports are enabled.- Check the MIDI cables for failure.- Try operating the MIDI interface at 1 mhz.- If using multiple ADATs, reduce down to one ADAT for troubleshooting.- Make sure that "Use Apple Serial DMA" is unchecked in the OMS preferences.