Material with a light function breaks after Lightmass calculation

Hi,
I have attached a nice neon sign to my scene. I set 3 materials to “light function”. Afterwards I assiged them to the 3D object. It looked really great. But after the Lightmass calculation the materials are now completely grey. The light function no longer works.

What is going on there?! Could this be a bug?

Best regards, Andreas

UPDATE:
I had to change the object parts with light materials to moveable. Then everything is ok.

Hi Andreas -

Light Function Materials are supposed to only be assigned to Lights themselves and are used to generate specific large scale shadowing (gobo effect if from live theatre or cookie if from movie background). They should not be applied to a Mesh directly.

Thank You

Eric Ketchum