Nodes Not effecting render?

Hello , I have made a very simple earth and added some composite nodes to try and make a atmosphere effect. However wen i render it the nodes seem to have no effect here is the file:;12085684;/fileinfo.html

Also I have tried using the one halo as my atmosphere but it does not really give the desired effect. There is probebly some setting i forget to turn on but i’m pretty new to nodes so i can’t seem to solve the problem.
oh also any other node layouts for an atmosphere or perhaps techniques would also be appreciated.

edit :apologies i have fixed issue now sorry for wasting time

Click Do Composite in the Anim panel, Render Context.
In the Node Editor header, click Use Nodes.
Select Blender Internal as your renderer.

thats a strange, neat planet. Yafray does not know how to do Blender nodes

The day that happens will be a happy day indeed.

Yea after posting this i found a vid which in the description revealed how to make the nodes work thanks for the response though