To upgrade from Datacom/AD 15.0 to 15.1 first install the Datacom/AD 15.1 software then perform an Active MUF Upgrade from 15.0 to 15.1.
You must have completed the process of upgrading your Datacom Datadictionary Version to 15.0 before performing a 15.0 to 15.1 active MUF upgrade.
The 15.0 Datacom/AD Multi-User Facility (MUF) should show these messages during startup:
DB00915I - CXX DBID 2 DATA-DICT DEFINITION VERSION 15.0 CHANGE LEVEL 0
DB00915I - CXX DBID 15 DDD-DATABASE DEFINITION VERSION 15.0 CHANGE LEVEL 0
Release : 15.1
Component : Datacom/AD
CAI.HLQ.INSTJCL
CAI.CHLQ.CUSLIB
CAI.CHLQ.CUSMAC
CAI.CHLQ.CUSPROC
After the upgrade to version 15.1 the MUF startup still shows version 15.0 in the DB00915I messages since there is no DD or DDD upgrade when upgrading from version 15.0 to 15.1.
See the Datacom/AD Techdocs documentation section Installing.