ais_shape not visible after upgrade from 6.2 to 6.5.3

hello,

i have a problem where code which used to display a 3D shape in 6.2, no longer does in 6.5.3. the objects are created, and they are selectable, yet only visible as the selection wireframes. otherwise only the new background gradient is visible, along with the moved trihedron. i have attached a picture of what is happening...

is there an api change that i am missing?

the code i was using is:

TopoDS_Shape shape = MakeNSided( ...params... );
Handle(AIS_Shape) aisShape = new AIS_Shape( shape );

theContext->SetMaterial( aisShape, Graphic3d_NOM_PLASTIC);
theContext->SetColor( aisShape, Quantity_NOC_ORANGERED );
theContext->Display( aisShape, 1, 1, Standard_True, Standard_True );

but clearly this produces different results in 6.5.3 than in 6.2?

my viewer is:

static Handle(Graphic3d_GraphicDevice) defaultdevice;
return new V3d_Viewer( defaultdevice, aName, aDomain,
ViewSize, V3d_XposYnegZpos, Quantity_NOC_BLUE3,
V3d_ZBUFFER, V3d_GOURAUD,V3d_WAIT);

from Peter Dolbey's old QtOCC code...

any help would be great, thanks!