Refueling truck

i have landed and parked at a gate in an airport (2 different ones to see if it was just that airport) and i pressed shift + f to call the refuel truck and a message comes up saying something like you are no. 1 for refueling its en route to you. But it doesnt work the truck never comes and doesn't re fuel the plane how do you get it to work?

The refueling truck ran out of fuel...perhaps?

Someone else has been having this problem, I'm not sure how to fix it, i think engines must be off and the cargo doors open or closed. Or I think I can remember somebody saying something about tail hooks.

You have to have the AI turned up and maybe the scenery also.
It can't be done at very low settings.

Do you have airport vehicles turned up?