I just tried again. My bad. I hadn't pushed the cable completely in. It has something to slightly block it to keep it from coming out, but it seemed to work in the opposite sense the first time I tried. Now that the cable on both ends is firmly plugged in...it works fine. Sorry.
I am new to flat screen TVs, and I just bought the Samsung 50" UHD model (UE50HU6900S) and am in the process of setting it up.
When it was delivered and the basics set up, the only HDMI cable I had came from some previous purchase - didn't need it before as I had an old analog TV without that option. The cable wasn't very long so it was connected to the more accessible HTMI 4 input on the TV and the other end to the TV decoder box. I have a Fibre Optics connection and TV service is through my ISP along with Internet, etc.
I wanted the option of a slightly longer cable so I went back to the shop and was told that for Ultra HD TVs he signal would improve with a better cable so I bought the Monster HDMI Ultra High Definition cable. Went home and replaced the existing HDMI cable with the Monster one. Turned on the TV decoder box and the TV and...no signal. Nothing at all - blank black screen. I know I plugged in the correct end since the cable comes with a tag near one end saying plug that end into the TV.
I don't know whether I need to manipulate something else on the TV to get it to work, but if so, I don't know what. I chose HTMI 4 from the Source icons. Could that particular cable be incompatible with the Samsung TV for some reason? It was recommended by the shop's TV salesman/expert.
I plugged in the old generic HTMI cable and the TV works fine.
While I am not new to computers - though I use Macs and Samsung seems seriously Windows oriented - I am unfamiliar with the flat screen inputs and technology so would appreciate any assistance or suggestions from forum members.
thanks.

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