While scheduling backup job  through OEM, I've encountered "ora-20446 the owner of the job is not registered". as workaround from metalink simply execute the following command using sysman user:


sqlplus sysman SQL*Plus: Release 11.2.0.1.0 Production on Thu Nov 13 12:14:41 2014 Copyright (c) 1982, 2009, Oracle. All rights reserved. Enter password: Connected to: Oracle Database 11g Enterprise Edition Release 11.2.0.1.0 - 64bit Production With the Partitioning, Real Application Clusters, Automatic Storage Management, OLAP, Data Mining and Real Application Testing options SYSMAN@ feco1>execute MGMT_USER_MAKE_EM_USER('DB_USER');


while DB_USER is the user that you use to connect to OEM.



Reference:
Doc ID 463874.1