These are the steps to diagnose the "javax.jms.Destination found at the specified destination-location" error an MDB in the Oracle application server (oc4j) environment.

1. The data source is correctly configured and connection can be successfully established. Test this from the Oracle AS em console.
   
2. The destination queue exists and is started. If you are using PL/SQL Developer, you can check this by right clicking on the queue name and make sure that "Enqueue Enabled" and "Dequeue Enabled" are checked.
   
3. Deployment descriptors are correctly set up.
   
4. The database user used for the JDBC connection pool has the proper privileges to enqueue and dequeue. Usually this means that the database user is assigned the AQ_USER_ROLE.
   

The ultimate test is to run some PL/SQL code in the oc4j test connection page to post or consume a JMS message.