[Hervé]

....... to get that shiny reflection, play with your UV, lower the settings, more shinier. what i normally use is UV of around .1 to .5 with glossiness at 25% and specular color ard mid to dark grey, lighter grey means more shinier.

hope this helps, from my short experience with Maxwell

funny thing is that in LW, if you set UV in Plastic anything but 0, glossiness channel is not working...