Maya character

While I was making my scene in maya, I imported the generic character to size things up. I tried then also to get used to moving it and how to move it and I have come across a problem. I am able to move it, legs, head and body but I cannot move its arms for some reason? Dues anyone know why this is and how to deal with it as I really want to start pre-vizing today but I want be able to unless I can move his arms.

Any help, you have my thanks.

Mike.S