stuck at "gate" on swamp boat

[liquidfunk]

Ive been cruisin on the swamp boat, made it over the jumps etc, but came to a place with a big gate. Ive got around and into the building, killed some guys, got some granades etc, but the valve to open the gate is busted. I stacked boxes on the cart to jump over the fence, but it wont let me. Im missing a weapon, ive got the pistol, machine gun, and granades but nothing between the machine gun and granades.

Any help? Ive spent 45 minutes trying to find it,,, I know its right in my face but I cant see it!! Im about to head the other way on the boat and see if its the wrong way.

see attached file for screen shots.

Thanks!

 

[hardcase]

At switch..look right at barrels..explode them.