Model3D Transparency

Hello.I have issue with displaying .ski model from Perfect World game.

In game one weapon should be like: 

but in wpf helix it looks like 

as i see,some details here should not be transparent,but they are :(.How can i improve this?

Code mark is default:

 <Grid Name="ViewGrid" Background="Silver">
            <hvd:HelixViewport3D Name="Viewport" ShowFrameRate="True" ShowCoordinateSystem="True" CameraRotationMode="Trackball"  >
                <ModelVisual3D x:Name="Model"/>
                <hvd:SunLight>
                </hvd:SunLight>
            </hvd:HelixViewport3D>
        </Grid>