What was the condition of your rear tires? Contis? PS2s? or?
US LC may not be as good as its Euro version but it's adequate to come out fast from a dig. Like Darren stated, you should never floor it all the way (unless you have drag radials and superior traction).

Before using LC you need to 1st TAKE UP THE SLACK by gently tap the accelerator (you will hear a slight clunk) BEFORE you start the LC sequence.

If you have very sticky tires, good traction and dry ground you can press the pedal to 3/4 depth like Darren stated, but if not, vary the depth between 1/3 to 3/4 to start. Once the LC starts, you need to slowly depress the pedal to the floor and KEEP IT THERE while changing gears! I would do all the gear changes when the tach reaches the YELLOW zone at 7,250 rpm(remember there is a "delay" within the electronics in addtion to our reaction time). Lots of practice will ensure better success at the drag strip...
Have a better launch next time and you will feel happy again!
PS: you DID turn the AC off, yeah?