vray alpha - with shadow

[monkeyman905]

I have an image i have rendered and want to do some post production, i have set up the alpha but it is only doing it on the object and not the shadow aswell. I have done it before a couple on months back but my mind has gone a blank and i cant remember how i get the shadow in the alpha map aswell. Can any one point me in the right direction please... im 99% sure its a stupid lil tick box some where!!

 

Thanks