High poly to low poly baking problems

[RazzMattazz]

Hi, im trying to bake shadows of my high poly model to a low poly version in max 9, but the problem is that it only bakes the areas where the high poly is above the surface of the low poly. Any ideas?
oh and i have set up the cage and stuff correctly it think, i used Ben Mathis' tutorial

[sage]

try hiding the low poly mesh model by going to element and hide faces

[RazzMattazz]

it did solve it in the end, i was not using the right renderer, it worked when i used a mental ray set up