SK880: You are correct (I was thinking of another product). The port used for midi clock is indeed determined by the common channel port (the actual channel setting is ignored as midi clock is a channel independent message).
Jon: Re the above (thanks SK), check that the common channel port is the same as the port you're using for midi in, (turn off LOCK if it's on). Of course, if your software can't send clock then you're still not going to get the desired result.
I do remember you from Akron music. Your rep at that time was, I believe, Jay Valle (not me, I never worked as a rep).
All the best