Error starting monitor: ...soapui-3.5.1/bin (Is a directory)

I installed soapUI on our openSUSE 10.3 server to try to debug soap messages over HTTPS, but when I launch the SOAP monitor, I get an error message that ...soapui-3.5.1/bin is a directory (which it is, of course), an INFO message is written in the soapui log that the monitor couldn't be started on the local port 8443 (in this case) and althoug the monitor window appears, it doesn't react when I make soap requests over port 8443. What is the program looking for when the monitor is launched and can I make a setting somewhere so it starts ok? Thanks!