First, go to the "Misc" Menu in the event log. Select the line that says "Enable Keyboard Commands."
I had the same problem with TCP connections. Here is what worked for me:
In the Command line for DSD+, include a -rp to set the receiver as passive only. This allows the program to use my Virtual Cable input instead of TCP/IP. I also included a -i2 to tell DSD+ to use my VC as the input.
You should be able to do this in the Menus as well. Questions?