I have a part model with numerous SurfaceBodies to be simulated as composite shells. To edit the definition of the shells under macro control I used SetPlyParameters2 to define various ply structures. Upon completion of the editing (using ShellEndEdit), the SurfaceBody shells under the study tree appear annotated with “…(-0 in-) (-Composite-)”, as if no thickness and no material had been assigned to the ply structure. However, when I manually look at the shell definition (using “Edit Definition…”) the ply structure appears correctly, as prescribed in my macro. Then, when I click the check mark, without having made any changes to the definition, the particular SurfaceBody shell just examined under the study tree now has an annotation of “…(-0.12 in-) (-Composite-)”, where the 0.12 in thickness is the correct total value for that shell. If I then, once again, edit the definition of the same shell, now the material assignment for each ply has disappeared. Needless to say, the whole simulation process comes to a stop if the thicknesses and materials are not properly recognized by the study. Attempting to mesh the structure gives a warning that “Thickness is not defined for one or more shells”. I could, of course, manually open each of the shells, but this defeats the whole purpose of expediting the process by using a macro. BTW, using UpdateAllComponents, rebuilding and saving the part do not seem to help. Is this a bug, feature or user error? Can anyone suggest a way out?