There is a setting in which you have to plug in the normal out and have it facing the camera. Is in setnormal function in the work area and this an extra attribute that will only be able to be plugged in this way. Will take some screen grabs if I have a chance to better explain. On iPad.....

Here is a blog that explains what I am saying better. Not how I learned but same concept.

https://matthewtan85.wordpress.com/tu...s-in-maya2011/