Why doesn't my DVI-I to RGB cable work?

I just installed a new graphics card for a media PC I’m putting together. It has VGA, DVI-I (dual-link) and HDMI output. Our current TV doesn’t have an HDMI port, so I bought a cable that converts DVI-I (dual-link) to YPbPr (the Red/Green/Blue cables).

When I plug it into the TV, the computer detects that a second display is plugged in and attempts to extend the desktop to the second screen. However, the TV just shows up a whole lot of fluro pink static.

Is there anything I could possibly do to fix this? Is this a problem with the cable or the graphics card? I haven’t been able to test the DVI port with a normal monitor yet, but the VGA port works fine.