camera.follow is only working in the x direction

[hac]

I created an animation where a green orb orbits a yellow orb.

 

Now I want the camera to follow the green orb so it appears as though the yellow orb is the moving body.

 

so I used camera.follow()

 

For some reason now it is only following it horizontally.

 

My project: http://phaser.io/sandbox/edit/EaDpkJrL

 

Thanks for your help!