If I understand the fractured english correctly, and fill in a bit, The
analog composite video out from the card is active, and you want the SVideo
output to be active instead.
Are you sure that you have an S video output, and not an input? Outputs are
more common.
Is the PC video mode set to a compatable resolution?
Is the analog composite video output disconnected from a load, such as a
video input to a tv or VCR?