Operation Flashpoint: Dragon Rising Tips?

Ok so i've had this game for a few days now, and i still haven't got through the second mission (where you assault skira island at night, and you have to remain undetected, destroy that thing [forgot what its called] then destroy the radars so the cobras can go in). I'm successful with the going in undetected part and destroying that thing, but then after i destroy the thing, i always get my team and me under attack even when we're all crawling in the grass. Somehow that barn place that you have to go to after you destroy the thing is where we die. Idk how to get past this part because if i decide to assault the barn, we just get flanked from the sides and behind. If i decide we'll wait until they walk away or something, we'll be too late and the cobras zoom in and the mission fails because the radars are still up.

anyone have any tips?