Revit :: Cannot Close Opening For Gambrel Shed Dormer

I have a shed dormer coplanar with the top chord of a gambrel roof.  When I try to use the dormer tool it will not let me select the shed dormer roof to close the loop.  There are no tools beyond picking appropriate edges/planes so I can't close it any other way than picking appropriate planes.  Why doesn't it see this roof plane as appropriate?  
 
Both the gambrel roof and the shed roof were created from extrusion since I couldn't figure out how to create a sloped roof from the dormer walls that was coplanar with the top chord of the gambrel without tedious manual calculations of wall heights or levels.
 
I've tried hiding/isolating uninvolved elements for easy picking and attaching/unattaching walls to roofs.
 
I also tried joining the shed to the gambrel which while successful in and of itself did nothing to work with the dormer tool cut the lower chord for the dormer walls.
 
I am aware there are manual methods to cut the roof and modify the wall profiles but I'm afraid that these methods will not join the elements in way that will produce a correct section or framing detail. 

AutoCAD 2010
AutoCAD LT 2013
Revit Architecture LT 2013