Glow appearing behing objects
 

I have a spotlight with a glow attribute (Optical FX Attribute) switched on, and i placed it behind a sphere. When i render this, the glow appears through the sphere. And this brings me to the following point: In the Transparency Shadows tutorial by Alex Alvarez on the Gnomon Workshop website, he mentions "fog shadow occlusion" - does this have any connection with the glow problem i am having?