The Right & Wrong Way to Edit Sheet Metal Parts

I was recently asked by a customer why he was not able to add a tab to a simple sheet metal part. It seems that when he added a tab to his bracket SolidWorks added another solid body to the model and the cut list. The answer was in the technique he was using or to be specific, the surface he was selecting to create the necessary sketch and resulting tab. Here's the starting bracket:

When he went to add the new tab, he selected the wrong surface to sketch on - in this case the top of the existing flange:

Selecting this surface adds the tab, but as a seperate solid body. This is the result:

The correct surface to select is the large back surface:

Which yielded the proper tab:

If you're having trouble adding tabs to existing flanges, make sure you're selecting the correct surface to create the new sketch on.