It sounds like you have ran into a problem with the version of HDMI that your currently using. What I would suggest is to look at the back of the monitor to see if there are any other plugs that you can use to connect to the computer.
Display port would be the best option but failing that DVI might work. If you have those ports and it still doesn't work then you might want to look at getting a graphics card (assuming your running the monitor of the built in GPU). You don't need a fancy one just something with the correct ports that can support the monitor(s) you want to run. Hope this helps :)