If they are the same color as the original entity, and/or change shades as viewed from other angles, it means that there is an error in the the shader it self:
It could be related to the bug I had to done a bug fix a few weeks back where I fixed an issue of the emit value being completely ignored from the custom shader, that should be present on return for
Check that the shaders always returns the emit value.
Make sure that the custom shaders return 0.0-1.0 and that should solve the issue. 0 => non emissive, 1.0 => emissive, while anywhere between is various levels of emissiveness