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

Hi,
 I have an electronic drumkit acting as midi master clock. Its connected to my XL7 which has the base tempo set to 0 (it says EXT). I can press start/stop on the drumkit and change the tempo, and the XL7 reacts fine.

The problems begin when I connect something else to the midi OUTs on the XL7. I have set Transmit MIDI CLock on A & B Out, but it does not seem to be transmitting any clock (it is transmitting note on/off quite ok). If I use the XL7 to merge the midi in to midi out A (or B), then I can send the start/stop messages through the xl7, but the clock messages are not arriving!!

If I connect the drumkit to the slave gear, it works fine, so the messages are disappearing inside the xl7, or the cables.. With this setup, if I change the base tempo to a positive number, so the XL7 is then the master, then the play and tempo controls on the xl7 are being transmitted.

I was pretty sure this has worked before, but I've been rearranging some gear and changes around some cables. Any suggestions for something that I may have missed? 

/ Niall