How do I sweep this curve around a closed profile?

Hi All,

Below I have a curve(blue) that I want to sweep around the filleted box. Trying to create a surface out of it so that I can thicken it to create a ziplok style container. Solid works just won't let me do it. I've tried all sorts of things and even made the line, that would be the center bottom face, into a construction line so that it wouldn't sweep accrossed itself and still no result. I must be missing something.

Thanks,

-G

SolidworksSurfacing