Next button disabled, but selected objects disappearing

Okay so I have placed a t/f variable so that the learner can't click the next button until three objects are selected; however each time the next button is clicked the layers do not stay visible.  Plus the learner could do this action and still proceed: click a picture (reveals layer text box), click next- activity directions pop up, click on two of the pictures and reveal layers and can then proceed by clicking next without all three layers being visible.

I have tried combinations of what I thought would be logical, but I am at a loss.  I have attached the activity in question.  Help! Oh great and all knowing Articulate community. :)