I'm have a fault code on my Lenze VFD and wondering if anybody could help me out with it.

I shut my vacuum pump off to do some work on my releaser, and when I turned it back on I got a fault code on the VFD. The vacuum pump will not turn on. The fault code is F.F_12. The manual says "AD offset fault". Does anyone know what this means and is there a way to fix it?

Thanks for any help.