S-video cable won't hook up laptop to tv?

I have an Acer Aspire 5520 and an RCA flatscreen (don't know what model, was a floor display). I bought an S-video cable to hook up my laptop to tv but it won't work. I turned the laptop off before hooking it up and turned it on the S-video input on the tv and it still says "no signal". What do I do?