SDiff Not Working

I got to the last part of the definition I am trying to write and I cant figure out why the SDiff component isn't working.  I have a list of breps running horizontal  and a list of breps running vertically.  I am trying to cut notches out of them so i found the intersection area and created a list of breps for these as well.  I figured I can use the SDiff component to trim the notches out of the first two sets.  This works great for the Horizontal Breps, but not the Vertical.  I know the intersect, and oddly if I flip the breps going into the SDiff component it works great, but gives me inverse results.  

Am I overlooking something?

I have included a screenshot of the definition since the file is fairly large and take 5 minutes to load.  

Please help me if you can, its all i have left to finish a project for school!