Brits NA 40 campaign - Italian Offensive problem

[PDiFolco]

This is the scenario where you have to retreat east and the exit your forces, the scenario rules forces you to occupy some hexes farther east every X turns, marked white then switching to british flag once occupied.
But on turn 18, while I do occupy all of the current objectives, I'm kicked out with a loss, as I still have one objective in white, even if I do have an arty unit on it !
Same if I put another unit there anyway... Is this a bug or did I miss something ?

[captainjack]

Artillery and AA units can't take hexes. If it's a 25 pounder, you can switch to AT mode but otherwise you need infantry, AT, tank or recon unit.

[PDiFolco]

Artillery and AA units can't take hexes. If it's a 25 pounder, you can switch to AT mode but otherwise you need infantry, AT, tank or recon unit.

Ok,thx a lot ! It's not said anywhere in the scenario ...

[Imeror]

Note that it applies to every scenario.