For some reason auto follow doesn't work half the time so you have to keep trying until it starts to follow.
I figured this out, and i actually wanna know if it could even be fixed (all you Fidelis)
Once you target something IE, attack it by hitting it, or targeting with a skill. Autofollow wont work 'till you leave area or relog. However. I have my BS on autofollow a lot, she can greed and still be in autofollow. Same with Slurpy, he can Grand cross and still be in autofollow.
thats all that i've figured out, i'm sure theres other things that kick it out of autofollow to tho.