title: Not able to connect to Oracle using Service Name
body: <p>I have hit a strange problem where I am not able to connect to Oracle as normal -
  username@service, and then type in the password.</p>
  <p>When I do follow this pattern I get the following error - ORA-12514: TNS:listener does not currently know of service requested in connect descriptor.</p>
  <p>If I type in with username/pwd@hostname/servicename it will connect. The tnsnames file is fine, it has never changed at all. It is also strange that this problem also exists not with one database, but with a couple of others.</p>
  <p>Can anyone give me some direction for a solution?</p>