never managed to get miter flange to work

i have been thru all the examples but this feature never works and i have tried off and on for many weeks now.

edge flange no problem but in spite of trying the examples to the letter there is some hitch somewhere .

i get the error message 'sketch not suitable for this ' or it just refuses to work at all.

is this feature buggy ?

its not rocket science copying the examples but for some reason ,no dice .

v2013

SolidworksSheet Metal