HelixToolkit SharpDX see through material

[KlaskSkovby]

I'm using helixtoolkit SharpDX, but i have an issue where i can see some items through the material.

I have added a hitbox, and put this material on it.

  var transparentMaterial = new PhongMaterial
  {
      DiffuseColor = new Color4(1, 1, 1, 0.5f),
  };

if i look from the front all other object of the same type is invisble but all other objects can be seen. if i look from the back there is no issue and the objects are seen.