Hit ORA-16796 when add DR via DGMGRL

DGMGRL> create configuration 'JKEPCON_DG' as primary database is 'JKEPCON' connect identifier is JKEPCON;

Configuration "JKEPCON_DG" created with primary database "JKEPCON"

DGMGRL> add database 'JKEPCONSBY' as connect identifier is JKEPCONSBY maintained as physical;

Error: ORA-16796: one or more properties could not be imported from the member

Failed.

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I have checked the 'drcJKEPCON.log' & 'alert_JKEPCON.log' with details below:

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2021-01-18T19:05:57.693+11:00

ADD DATABASE

2021-01-18T19:06:01.832+11:00

Failed to connect to remote database JKEPCONSBY. Error is ORA-12504

Failed to send message to member JKEPCONSBY. Error code is ORA-12504.

Error: importing database setting from the remote site failed: err=12504 lvl=2 db="JKEPCONSBY" cid="jkepconsby"