First, you don't have to press the buttons.... You can just jump to the area you need to be to shoot the arrow from. Practice with cheap arrows until you hear the "thunk" - don't move your aimpoint, equip the arrow of extrication, then use it. No problem.
Don't know what to do if it won't let you fire it. Didn't happen to me. Try equipping/unequipping several times. I'd say drop it and pick it up but I don't think it will let you do that.
