Help With Mates

I

need help with mates in the attached file.  BAsically I have a bunk assembly that is inserted in a box assembly.  The box assembly has sloping walls.  The bunk has angles on either side that need to move in and out based on the distance of the bunk from a floor line.  The bunk assembly has limit mates that allow the angles to move, but only the amount the bolts travel in slots.  I mate the edge of each angle to the coresponding sloped wall.  I mate a line in a sketch to the sloping back wall.  When I try to put in a distance mate from the floor to the top of the bunk I get an "over-defining sketch" error.  Anyone have any suggestions?

SolidworksAssemblies