NO signal

[Hophoto]

I just hooked a LG Tv.. to a new adapter and installed the update.. on my IMAC with lion 10.7.4 and all I get is no signal... the mac will see and identify the Tv.. and give me a choice of Res.. but no way will it work.. I even swapped HDMI inputs and cables... but no luck.. any ideas..???

I have one set up working perfect... and this one is mess

[jenismo]

RCA HD TV, OS X 10.7.something, just the screen flickering between blue with no signal and black.

What's the deal here? Thanks!