... i really dont know.. all i can think of is perhaps its useable only with a rifle then, as special attacks should be useable with normal weapons, i'll have to check commando again i guess. your definitely sure the special attack isnt working when you try to use it with the carbine? the simplest way to determine if a skill will work with a weapon, is when you equip the weapon, x's appear on the icon, as in x can't use skill, make sure your in range too, if your in range to hit with the weapon, and the skill shows an x, then it can't be used. if there is no x, make sure you are activating it correctly, you can activate a skill by either pressing the associated number to go with the skill, 1 for box1 etc or, if you have it by right click activation only, have the skill selected and then right click to use it. hope that helps...