I'm on StrongPoint, check point 7, trying to destory the big guns, I target guns and give comand to attack, chopper pilot answers ok, then nothing. Why?

try the game guide here.
http://guides.gamepressure.com/ghostreconadvancedwarfighter/

Thanks, great web page.
It didn't help, I've played the level over four or five times same thing! I've killed everyone, even shot my own men in the end, just out furustion!!! Ha! I think I will try switching guys like was hinted by someone on page you sent me to.

I went back and did level over but gave all of the team a rocket launcher. We were able to kill the tank cannons, without the chopper.
Thanks for the help!