Assigning different decks to the same floor level?

I have a building that has a high and low roof.  The low roof is the same T.O.S. as the 2nd story.  The 2nd floor construction is conventional 5" one-way composite slab on deck and the 1st floor roof (low roof) is a flexible EPDM roof.  After I model slab edges and assign decks to each respective area, I encounter one of the following issues:

1) The Gravity Load Data Check returns errors that the slab edges intersect and gives a User Action to create separate (non-intersecting) slab edges.

2) When assigning a slab edge offset from one another, I receive the same error in addition to another error: Break or extraneous slab edge detected with a User Action to delete extraneous slab edges or make slab edge continuous.  In addition to this, after I assign slab edges to split the two decks, the options to assign each deck under Graphics Mode of Deck Assign Mode ("Whole Floor", "Whole Diaphragm", and "Add" buttons) are grayed out as not being available.

I've tried multiple things from deleting the slab edges all together and starting from scratch, changing the slab edges, etc.  Nothing seems to work.