okitvv26td: the computer can't be seen on hdmi

You need to provide a little more data to help you. For example is a notebook or desktop PC? Before it was working or is it the first time you connected it and it doesn't work? You could try replacing your HDMI cable if it worked before or verify in the graphics properties that it is correctly configured by sending the signal to the screen where the HDMI is connected. Regards...