Trouble Adjusting Aperture - Getting "Select AF" Msg

[tarinfrantz]

Hello! I have been shooting with my Mark IV for years, in manual, and just the other day it started giving me the msg "Select AF" when I attempt to change the aperture. It is not the lens, as I have taken it on and off and get the same msg. It is not the lock switch on the back of the camera or on the lens and I have unlocked both. I also have my lens switched to AF on the little switch. It is also not the aperture range setting as mine is currently set 1 - 100.  Does anyone know why my camera is telling me to select  AF? 

[Anonymous]

What camera are you using?

If a 5d MkIV, is one of these buttons stuck down?