Commandos 2: mission number seven.

Good morning.

First of all excuse me for my English, but I am italian.

I have recently bought Commandos 2 and i am playng it, but now I am stuck a
the 7th mission, the one titled "Haiphong's giant" (i hope the English
title is right). I have rescued all my commandos, including Natasha with
her chinese cloth. A this point i should send all the characters in the
truck in order to enter the german base, but the truck doesn't move,
whatever I try. Surely I am doing a mistake, but I am unable to find it. I
have read a couple of solutions, but I found no useful information.

Could someone help me?

Thank you in advance.