How to make a slot on sheet metal bend bracket?

Hi

I would like make a slot on a bending bracket (see below), but when I set flat pattern on this bracket, it like this (see below), which is not real slot. I tried to make slot on the flat pattern, but it didn't show when you bend the bracket (which after flat pattern command!). Anybody know how to make a real slot on flat piece and when you bend the bracket, it will show this slot cutout.

Thank you very much

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SolidworksSheet Metal