Just experienced this issue today in my office... guess I'm just a bit shocked. I didn't realize HDMI had a distance issue.
Apparently there's trouble over 60 feet? Now I have no solid confirmation of this. Sorry, I'll explain.
We picked up a few HDMI Splitters. Tried 3 HDMI links to some sweet Samsung panels, 4 twelve foot cables in total. 1 from source, 1 per TV. Everything worked completely fine.
So... we had to move the source... routed the HDMI through the ceiling.
1 12 foot per TV (3 12' HDMI), 1 60 foot to source. ...No signal. After reading further it said that the splitter itself couldn't handle more than 60 foot total between source and destination. Was wondering if anyone might be able to explain why this could be? I'd like to learn to better understand future setups. If it helps... splitter had it's own power source.