Problems when exporting to step file format ( Solids become surface)

I'm using the NaroCad Wrapper, for my OCC application.
I create a cylindrical shape with the (OC)BRepPrimAPI_MakeRevol with rotation angle = 360.
I also check that I have a closed wire before i revol it to a cylinder.

So far it look like an Solid when Im viewing it with the Open Cascade API.
But when I'll try to export it to Step and viewing the model inside Inventor,
It seems like the Solid Cylinder shape has become an surface. It's missing to bottom surface.

My Export function look like this: (C#)

using (OCSTEPControl_Writer writer = new OCSTEPControl_Writer())
OCXSControl_WorkSession session = writer.WS();
for (i = 1; i {
OCIFSelect_ReturnStatus status = writer.Transfer(shape.Value(i),
OCSTEPControl_StepModelType.STEPControl_ManifoldSolidBrep, true);
if (writer.Write(sfd.FileName) != OCIFSelect_ReturnStatus.IFSelect_RetDone)
throw new Exception("Could not save file!");

As you can see, Im using StepModelType = STEPControl_ManifoldSolidBrep , is that wrong ?
Is it some kind of function I could use to check if I have a 100% Solid object before I export it,
And is it possible to fix/heal an object if its not a solid?

Best Regards

Test user's picture

I forgot to mention that for those object that I'm
using the BRepPrimAPI_MakePrism function, will still
be solids after exporting to step and viewing in Inventor

Test user's picture

I finally figured it out.
Wrong Geometry...