Don't know if this still needs fixing.
Things to try:Try changing the Resolution, a Resolution that the TV can not handle will result in "no signal"
make sure Secondary monitor is Enabled - There may be a button on your keyboard that enables it.
Posting your exact laptop model, i can explain more accurately on what to do .
............................................................................................Main System Spec: Intel Quad Q9550 (OC to 3.4Ghz), Gigabyte Ga-ep45-ud3l, 4gb kingston hyperX @ 1066mhz, Corsair tx 650, Nvidia 8600GT.