New video card will not do dual monitors?

I just bought and installed an ATI Radeon HD 4670 (2 DVI outs and 1 S-Video out), im trying to run a regular FPM and use my HDTV as my second monitor, using a dvi to hdmi convertor, when i plug in the tv and goto the ati control center it detects the tv, even tells what model the tv is, how im connected everything,it is even enabled as my extended desktop, but no picture? same happens when i connect an s-video cable, when rebooting the screen will flicker indicating that there is some sort of signal getting there but when its fully booted no picture... anyone have any ideas?|||What's your screen resolution set to? It's possible the TV can only display it's native resolution.