This error appears when trying to add an MDISK to a user:
ACFDMB3951E 58AE DIRMAINT: Command rejected, user USER001 not authorized
ACFDMB3951E 58BE Command-> FORUSER USER002 REPLACE
ACFDMB3951E 58CE USER001 not authorized for AMDISK on volume VOLXXX
Release : 12.0
Component : ACF2 for z/VM
zVM: 7.2 RSU 2201
These errors can be caused by an upper/lower case problem. Check the CONFIG DATADVH Language setting. AMENG supports mixed case and UCENG only supports upper case.