Emu XL-7 & MP-7 User's Group

HI FOLKS,
SEEMS LIKE THIS SHOULD BE SIMPLE ENOUGH BUT IT HAS ME STUMPED.
I USE MIDI ALMOST EXCLUSIVELY FOR THE CLOCK SO I CAN SYNC UP ALL MY 
UNITS IN SERIES AND THIS HAS ALWAYS WORKED FINE UNTIL I INSERTED THE 
XL-7 TO THE CHAIN.  
HERE'S THE PROBLEM: THE XL-7 RECEIVES THE EXTERNAL CLOCK FROM THE MIDI 
SOURCE JUST FINE BUT WILL NOT TRANSMIT THE EXTERNAL CLOCK ON TO THE 
NEXT UNIT IN THE CHAIN.
THERE IS NO PROBLEM TRANSMITTING THE INTERNAL CLOCK FROM THE XL-7. SO 
IF THAT WORKS WHY WON'T IT TRANSMIT THE INCOMING EXTERNAL CLOCK?
I HAVE READ THE MANUAL AND HAVE DONE THE FOLLOWING:
I'M IN MULTI-MODE (TRIED OMNI & POLY)
BASE TEMPO IS SET TO EXT.
MERGE MIDI IN TO MIDI OUT SET TO OUT A = ON, OUT B=ON (NOT SURE IF 
THIS MATTERS)
TRANSMIT MIDI CLOCK IS SET TO ON.
CLEARLY I'M MISSING SOMETHING. ANY HELP WOULD BE APPRECIATED!
-JEFF