Add Corner Trim to a sheet metal part

Hi, Guys!

I'm new to SolidWorks and I'm having some trouble in the cornerreliefs in a Sheet Metal part. I need to add a square cut out inthe bent up corners. And I don't even have the option of addingthis style of corner trim. I have the normal auto-relief options(rectangle, obround & tear) and I am using the tear option forwelding that is going to take place. I have tried the Help optionthrough SW, and I have surpressed the Flat-Pattern option but imnot even get the option under 'Corner Options' all I get is 'cornerTreatment;. I'm just not sure where to go from here since it's notthere as an option. I have also tried the Insert, Sheet Metal, AddCorner Trim, but that is just a faded picture where I'm unable toeven select it. I would greatly appreciate and all help, advice anyideas that you guys might have. Thanks!!!SolidworksSheet Metal