sheetmetal unfold does not work

Hi There,

I seem to have trouble unfolding my sheetmetal parts. Therefor I tried to make a simple cube, convert it to sheetmetal and then unbend the sides. But it still gives the same error.

Personally I think my Solidworks is corrupt. Collect all bends does not work also. I have to manually pick them. But still the eroor message: this part contains features that cannot be unbent

Does anyone have a clue?

SolidworksSheet Metal