configure PortServer TS 16 Rack to work with several PC's

I have a PortServer TS 16 Rack.

I am working with Virtual machines ( Vmware )
and I want to connect to every VM a single com port with the DIGI PortServer .
the OS on the VM are Windows 7 / Windows XP.

The problem I encounter is that when I install the Digi RealPort Driver & Setup Wizard (Version 4.5.372.0, 04/19/2013) i am only able to set all 16 ports on the same VM PC.
When I try to configure only one port as
I am getting a single port that is mapped to the port #1 in the PortServer TS 16 Rack.

There is no option to change the port number in the DIGI that is mapped to the .

please advise