Of course I wish you to be more direct, instead of "turning around the pot": I like to know what I am speaking about, not speculating about somebody (in this case you) telling me this or that does not work without background information and clear picture of the situation.
This being said, I can only imagine that there was an issue with the AF mode chosen (spot, center weighted or average), and I believe this issue has been explained and addressed in David's case.
As for your dealer where you tried this out and where you had this problem: it would be nice to know which Sinar dealer this was, that we can contact him and ask about this problem with this body, which I suspect to be an early prototype with the very early firmware: those cameras are from the o-series and should have returned to Sinar. If you feel not appropriate to post the dealer's name here, you can PM it to me, but in any case I wish to know that we can have a look at it.
Thanks and best regards,