Crysis Help

I am stuck up at one stage in crysis . In that I have Destroy the Alien Exosuit , But how to lock target , binoculars show a symbol of alien exosuit but dont lock it
Answer #1
I dont get you, I’m sorry.
Answer #2
I shoot the mouth. Doesn’t matter where I guess.
Answer #3
You mean that thing in the sea ? Perhaps you havent taken out all of the guns yet, and the thing is still shielded. Or, you should try simply aiming and it should start charging the gun.
Answer #4
Finished crysis , I was trying to use the special gun everytime but it was meant to be used only for the last one