How can i get brushes to use lightgrid data for vertexs?

[gareth]

as stated.

[vcxzet]

textures/poo/brownpoo
{
   {
      map textures/poo/brownpoo_poo.tga
      rgbGen vertex // -> this one?
   }
}

[gareth]

textures/poo/brownpoo
{
   {
      map textures/poo/brownpoo_poo.tga
      rgbGen vertex // -> this one?
   }
}

however it doesnt work v.well, sometimes it is fullbright, sometimes it seems to be the colour that it should be (func_plat) when it is at the bottom location. using rgbGen vertexLighting also seems not to work.