imac not detecting display

Hi, Im trying to connect a 40" lcd 60hz sony tv, with an iMac 27" i3 3.2ghz.

Atm tv is running Hdmi cable into a hdmi to mini display port cable which is plugged into the iMac. Now the problem is the iMac does not detect the tv.

I've tried restarting the computer with it plugged in, without it plugged in. with tv off, with tv on... I've tried detecting the display, i also tried the adapter on another computer and it works fine, I plugged in a apple cinema display and it worked right away.

Any suggestions on what I can try. i know the tv works. i know the cables work, i know the port works. I'm running out of ideas. Any help would be much appreciated.

 

got it

So i went to work and picked up a different brand hdmi to mini display port adapter, and it works now.. So my iMac doesn't like the hdmi adapter but it works on my mac book and mac mini...

 

Wirelessly posted (Mozilla/5.0 (iPhone; CPU iPhone OS 5_0_1 like Mac OS X) AppleWebKit/534.46 (KHTML, like Gecko) Version/5.1 Mobile/9A405 Safari/7534.48.3)

I switched to a moshi connector and it works no problem now. So I'm happy about that, but it's still weird every now and then I get a grey background but any windows open are still visible