MTP Catch 22

[Sparks]

Hi all

I've been trying to sync together my 002r (6.7) and a Presonus Digimax using a MTP-AV (the older one without USB, using the printer port). I've used the MTP as the internal clock source, driving the Digimax word-in BNC, with the 002r set to external clock from the Digimax lightpipe out. I can control ProTools by MMC sent from the MTP by a LRC and all is good. However, when I try to use ProTools as the MMC master, the MTP has to sync from MTC generated by ProTools using the external clock from the Digimax. This shows timing errors of +/- 20 on 48000. How do I use the MTP as a clock master, but a MMC slave? Do I need a diferent independent clock source?

Cheers
Sparks