failed to add rip. please check the rip gap specified

Hi,

I am trying to convert this part to sheetmetal, however when i try i get this error

"failed to add rip. please check the rip gap specified".

The only thing strange about it is the bottom flange slopes down slightly (the reason i am creating the part this way), other than that i dont know what the problem is.

Would much appreciate being pointed in the right direction

SolidworksSheet Metal