Help! Connecting Computer to HDTV

I am attempting to hook my computer to my Samsung Slimfit HDTV (using a DVI to HDMI cable).

However, my TV still says "No Signal" after playing around with all of the display options in ATI Catalyst Control Center.

I did read somewhere that older HDMI versions cannot display computer signals. Could this be the problem?

Any ideas would be appreciated,
thatsinsane