TeknoMW3 is on version 2.7.1.3, and most servers are probably 2.7.1.2. Just update and it should work.
I reinstalled my MW3, I put the Tekno 2.7.0.1 to play, and ok, when I click on "Start LAN / online" appears the window "game is running", and nothing happens. Have tried several updates, and none of them gave results can anyone help me?
TeknoMW3 is on version 2.7.1.3, and most servers are probably 2.7.1.2. Just update and it should work.