Storyline 360 : Variables

Hello There,

I am trying to solve a problem with variables. The easiest way to explain it is like this:

I want to roll a dice, I click a roll button.

What I want to happen is for the dice to roll a random number (1-6).

If the number has not been rolled before then the dice will display the result. If the number has been rolled then the dice is rerolled until a number displayed is available.

Once all numbers have been rolled then a layer comes up to say no more moves / available numbers.

I have attached a file I have been working on. I cannot see why I still get duplicate numbers. 

Any help would be much appreciated.