Surface thicken

Hi all¡¡

I am triying to create a thicken surface from a revit generic mass model…someone knows why says to me this king od erros:

-LOP_TWK_NO_LOOP – no loop through new edges and vertices
-Unable to compute shell : REM_NO_SOLUTION – gap cannot be filled

I have tried in 100 ways but is imposible…anyone knows how to do that?ç


Could it be that surfaces are intersecting themselves?