If you are not able audit data to database for OID and OHS after modifying the opmn.xml.Verify after doing the below steps.
1.Set the environment variables example
export ORACLE_HOME=/u01/app/oracle/product/11.2.0/dbhome_1
export ORACLE_INSTANCE=/u01/Oracle/Middleware/Oracle_WT1/instances/ohs
export COMMON_COMPONENTS_HOME=/u01/Oracle/Middleware/oracle_common
2.Follow the steps from “12.2.4 Configure a Database Audit Store for System Components” from http://docs.oracle.com/cd/E17904_01/core.1111/e10043/audpolicy.htm#BABIDHII
2.Remove the below to entries from opmn.xml after doing all the above mentioned steps and re-start the components
-Dstore.password=true
-Dauditloader.password=password
Oracle Identity and Access Management Learnings 