cat 311 wont go above idle?

Have a cat 311 that will not go above idle . There is an A on the display which the book says that it mean its in manual mode. On the manual switch behind the right hand armrest it is in auto. If i turn these switches to manual and push the increase or decrease button the machine will rev up or slow down . The selector switch is reading 1-10 like normal . How can i get this back to auto? Thanks