Revisit slide at head of a branch

I have one slide with twelve objects, that can be clicked in any order.  Each object becomes Visited (and stays that way) and will take the user to another slide in the course and return to the main slide after viewing.  I have the NEXT button disabled when timeline starts until all twelve have been visited.  That trigger works perfectly.  BUT, when the "twelfth" slide in the branching returns to the main slide the NEXT button disables again.  I have it set to "resume saved state".  I have tried trigger "set NEXT button to Normal when timeline starts, if all of the objects are visited".  No luck.  What am I missing here?  Please help!