Stuck on R6V

[unlockthexbox]

On Ranbow Six Vegas and on the mission spillway, I can't get the floodgates to open with my team mates. I send them upstairs, lay some C4 on the ground right next to the shutter door and get into position but I always either die or run out of time. Iv'e replayed countless of times, I just want the game to end but I can't. Iv'e tried every possible combination of grenades, guns and positions but still can't continue. I'm getting sick of this now. Please help me.