@Acrionx: Some tips for glow aurae:

Reduce eccentricity. That is, smooth out sharp bends. For example, if you make an aura for a cube-shaped lamp, the aura needs to be closer to a sphere in shape, with just a hint of the cube shape. Use your modeler's smooth command! Otherwise, the edge_blends will zero in on the sharp bends, making those areas nearly opaque, while the flatter areas disappear.

Higher polygon density improves aura render results. Especially for a long cylinder (neon tube, or lightsabre blade), you'll want to put lots of loops along the length of that tube, otherwise only the ends will show well. Even for relatively round shapes, like that torch flame aura shown above, more polys will even out the opacity. I often subdivide aurae in Poser, sometimes two levels.

Poser 12, in feet.  

OSes:  Win7Prox64, Win7Ultx64

Silo Pro 2.5.6 64bit, Vue Infinite 2014.7, Genetica 4.0 Studio, UV Mapper Pro, UV Layout Pro, PhotoImpact X3, GIF Animator 5