Thanks for the reply Thomas.
Yes I started with the very latest Pktriggercord and have tried several older versions and on several Ubuntu versions just in case.
All those work with my K200D but
not the K10D.
The K200D is mostly a K10D under the hood and both cameras work with PKtether.
Thus we can probably dismiss hardware and Pktriggercord as being the problem which leaves only the firmware and, most logically, the Remote Assistant compatibility in the K10D as being the hurdle.
I had hoped it would be something simpler that perhaps even I could fix.
I have just emailed Andras the details and will follow up your suggestion of using the cli option tomorrow.
I guess I should have started Pktriggercord from a terminal and looked for what errors it is throwing...
.. I will try that tomorrow too.