Cubase not reading Midi in from Midioverlan

Hi :

Computer A with cubase , port 76 as midi out, computer B with pro tools , port 76 as midi in, receives everything perfectly. BUT: Computer A with cubase, port 77 as midi in , comiputer B with pro tools, port 77 as midi out, sends midi to computer A, VI pro receives the midi message perfectly, but Cubase didn’t/couldn’t read any incoming messages-(all ports in Cubase midi port setup is selected)
All other phsical input Cubase can read…