3D symbol is rendered as 2D symbol

[PhilippeSteinthal]

I am trying to render a simple cube but it is always rendered as a square when I tilt the globe it is just flat.(works fine in ArcGlobe).Any idea?
Thanks


string name = "Cube";
string category = "3D Geometric Primitives";
string fileName = "3D Basic.ServerStyle";
....
IStyleGalleryItem styleGalleryItem = symbologyStyleClass.GetItem(i);              
symbol = (ISymbol)styleGalleryItem.Item;

[PhilippeSteinthal]

I have done some more testing and if I change the symbol of an added shapefile the cube is renderered correctly.What could I be missing in my custom feature layer?
Have no clue...
Thanks

[PhilippeSteinthal]

...found the issue.
In fact it was not due to my custom layer but to the fact that the geometry was 2D and not 3D.
(not z aware).
Why does it make a difference?