Not sure which provider you are using in Terminal Session activity.
There are two ways for Personal Communicator:
Try them both.
The second needs you to point at the EHLLAPI DLL so see tips here, together with recommended EHLL settings in each case:
If none of them works, check the security settings (antivirus, Group Policies).
The direct provider needs to connect to Terminal Emulators COM interface (so security settings might prevent that)
The EHLLAPI connects to “another applications” API implementation’s dynamic library (namely the EHLL API dlls in pic above) and this can be disallowed by security settings as well.
One last note: there is a short session name associated with a terminal emulator display (it can be A, B, C etc and it’s displayed somewhere in the lowest bar of the terminal window, can’t quite locate it precisely right now as I don’t have a Personal COmmunicator at hand). The EHLL settings has a Short Session Name that must be the same as the one in the Terminal Emulator, otherwise it will not connect.5