Corner Block adaptation, 1 inch Bent aluminum corner-McGeen

Here is what I was able to accomplish today and the problems that I faced getting to this point.

First off, this corner bracket has taken me much longer than I expected, especially for a novice such as myself. The Corner bracket was originally from the Mendel90 but will replace the slotted joints and nut traps in the Fab@home.

 I also constructed a corner bracket for a much easier assembly made from a 1.5"x1"x 1/8" piece of aluminum. Knowing the hole size from the Mendel90 corner bracket, I moved the curves to the solid and used a boolean difference to bore the holes.

And finally problems with the major fab@home file, er not with the file but with my own construction. What you are looking at below is the updated front plate with a connector piece that connects the two sides. After I deleted all the nut traps and added this horizontal connection, I kept getting a error message that stated, 

"Two inputs were not extruded because they would have made invalid surfaces." 

I believe maybe the issue is an overlapping or intersecting curve that is throwing off the proper extrusion, but below is what happens when it extrudes.