I'm trying to add tabs and slots onto a round tube thats mitred or coped around another tube. We are planning to send this out to get laser tube cut. The problem i'm having is the tab and slot feature in solidworks dosen't recognize the edge of the tube. I know i could probably add the slots and tabs manually using boss extrudes but would like for an easy method as there are a lot of tubes that need this feature. Anyone run into this issue?

Below is what i'm trying to accomplish. 

And below is an image of what happening when i attempt it. (the red line is the edge i'm selecting)