Offesting a polysurface...I need help URGENTLY!!!

I try to give thickness to a lofted surface. I explode(BRep components)
the surface and gain the faces of it. Than I offset(offset surface)
these faces of the polysurface but at the filleted corners of the
section curves the surfaces are not continuous. I would like to eleminate the openings at the rounded corners of the surface. I also attached a picture of the problem and the definition. Help is very much appreciated from anyone. Thank you for reading this