Basic logic problem

Hi, all!
I have this very basic problem (Harlowe 1.4):

$grille01 is set to zero in the header passage. The current passage is Grille01.

(print: $grille01)
(if: $grille01 < 2)[The grid is rusty, so much so that you'll have to push it.
(set: $grille01 to it + 1)Do you want to [[push the grid|Grille01]] ou [[stop the game|Abandon]] ?]

(else:)[Zut]

When I click "push the grid" I go back to Grille01 as designed, but $grille01 is not increased by 1!

Thanks