WHY CANT I USE THE LAUNCH ATTACK IN FINAL FANTASY XIII?

in final fantsy 13 i cant use Lightinings launch attack. I upgraded the attack in her commando crystalarium but in battle i still only have attack, blitz, and ruin. i have 4 slots to put an attack in but theres no option to but launch in. when im using lightning as a computer and im using some1 else she uses it.... Y CANT I USE IT?!?!?!?!?!?!?!?!