Database Configuration Assistant was not showing the database

Database Configuration Assistant was not showing the database and  Configure Database Options and it was disabled.
 
 We tried setting up ORACLE_SID and ORACLE_HOME and ran dbca but it was not showing the database and the above option was  greyed out.

We checked and verified the oratab file for correct entry for the database we were trying to access from dbca but still it was greyed out.

To resolve this issue I utilized all my experience and knowledge at last was able to resolve it. The issue was simple and silly but sometimes small things matter.

Below are steps used to resolve this issue:

Step 1:

Make sure the ORACLE_HOME is some thing like below : /u01/app/oracle/12.1/dbhome in /etc/oratab file

(Note we should not have '/' after dbhome)

Step 2:

Check the value of the configuration of  RAC Database:

srvctl config database -d testdb1

Where: testdb1=> DB Name.

Now change the ORACLE_HOME value as below:

srvctl modify database -o /u01/app/oracle/12.1/dbhome

Where:  /u01/app/oracle/12.1/dbhome=> ORACLE HOME location.

Make sure you don't use '/' after dbhome.

Step 3:

Now launch 'dbca' bye setting correct Environment.

Now you should see the option enabled for Configure Database Options after launching dbca.