baking a AO map from high poly to low poly

Can anyone help:

I am trying to bake an AO map from a high to low poly mesh.
I keep getting a map which is much brighter on one side than the other and can’t work it out.

I have removed all lights, I have tried using a using a cage which is outside the high poly mesh.

Every time it comes out like this? it should be much more even.

When i don’t use a cage it comes out like this:

thanks for any help