If you want to wait the answer from Oracle Support here.. you'll need a lot of patience.
Is the corresponded Database Connection test succeed?
If it also fails that, I think, your JDEV_MDS user (schema) lack of the CONNECT privilege.
A question to you - how did you created this schema?
You should use RCU to create the schemes for SOA Suite (and other Oracle Middleware).
The RCU creates the schemes with all necessary structures (tables) and grants.
Hope this helps,
Thank you very much for your response.
Yes, I used RCU to create the schemes, and I can create Database Connection using "SYS" and tested success. But I can't create Database Connection in JDeveloper using JDEV_MDS account. I also can connect through some SQL tools using JDEV_MDS account, such as SQLDeveloper without any problem.
Because I can't complete Database Connection with JDEV_MDS account, so can't continue creating Database-bases MDS connection.
Thank you again for your reply.