lappy to tv help, cable won't work

ok, i bought this cable:

http://cgi.ebay.com/ws/eBayISAPI.dl...MEWN:IT&viewitem=&item=230042607140&rd=1&rd=1

to connect my lappy to the tv. i have the sound connected via 3.5mm jack to rca and that works just fine, but the video does not come thru. all i have is a black screen. i went to display in the control panel and i get an option for the second monitor, however when i hit the "identify" button, all i get is static on the tv for a couple seconds and then it goes black again. it is currently connected via the rca cable, should i maybe use the s-video component? will that even matter? please advise.