hmm. I can't say I'm having this issue, but I'd be willing to help...
Are you trying to connect over USB, or network?
First off, make sure you have the proper device selected for the connection profile.
If USB, go in GCC, Connection Admin, open the specific connection profile and set Type of Connection to RS232/USB, and Interface COM: AUTO (it's above com 1)
If Network, go in GCC, Connection Admin, open the specific connection profile and set Type of Connection to Network (TCP/IP) and set Host-Name: {whichever IP you've assigned to your P4/Doser/Mitra)