Mode not supported computer to tv

[qwiknic104]

i just bought a brand new HP with windows seven on it. i am trying to do a "duplicate" display on my screens. one of them is my regular montior and the other is my 50 inch samsung tv but whenever i click on duplicate display it says MODE NOT SUPPORTED on my tv. i am using the GVA i believe it is, the BLUE plug for my tv and the white one for my montior. so i went and bought a graphics card thinking it would help and it hasnt. i still see the mode not supported on my tv but my computer down here in my basement is fine. and ideas? i'm running a 50ft GVA "blue plug" to my tv since its upstairs and my computer is here downstairs and i want a duplicate on it. so whatever im doing here on the computer will show on my TV upstairs.

 

[dudewitbow]

So right clicking desktop > Personalize > Windows Mobility Center(i think this is for laptops) > Connect Display > Mirror My Desktop doesn't work?