Problem capturing s-video signal from GeForce 7300GT on PVR-150

I have a GeForce 7300GT and a Hauppauge PVR-150 capture card in the same computer. I'm trying to run from the s-video out on the 7300GT to the S-Video input on the capture card. I went into the nvidia control panel and enabled multiple displays, and the secondary display defaulted to TV. After this, when I go into WinTV (the capture card software) and choose to display from the s-video input, nothing shows up, and then the option for s-video is not selectable. What am I missing here that doesn't allow me to do this?


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