Scratch

Hello, I would ask you one question please.

I'm doing now a game in scratch.. it's about 3 boxes in the left, and the player have to drag and drop it in the right place.
I want if the player drag and drop the first and the second in the third box in the right place, then switch background custom and show sprite"you win!".

but I have a problem, i programmed as:

if "box1" touching (yepbox1).. set variable to 1

if "box2" touching (yepbox2).. set variable to 2

if "box3" touching (yepbox3).. set variable to 3

if variable = 3 go to change box's custom

then

if "box1" touching (color#).. set variable to 4

if "box2" touching (color#).. set variable to 5

if "box3" touching (color#).. set variable to 6

if variable = 6 go to change broadcast "the end"

the problem is: if the player first drag and drop box3, the variable will be 6 and the will end with out dragging and dropping the box1&2!!


And thank you.