[Zope] Zope3 on Ubuntu 64

I've installed Zope3 on a 64 bit Ubuntu platform and all seems well. I've run mkzopeinstance and the instance directory is there and looks ok. However, when I try to start the instance, it says [fail] for the zserver instance and there are no entries in the z3.log file. The default instance chosen was 9673, not 8080. I wonder if that's saying it's not finding an available port. But I've port scanned the machine and both 9673 and 8080 are open. Any ideas what to try next? How do I enable more logging output? Thanx in advance, Brian