Oh, how I hate that message. It's obscure, it's confusing, and it's just plain wrong.
Since you didn't throw a NamingException, it looks like you did connect to a Connection Pool Object, and the message implies that attempts to create and add connections to that pool failed.
There are 2 things that I think might be a problem. First of all, I think it's "oracle:
jdbc:thin@hostname....", not "oracle.jdbc.thin
:@hostname... Secondly, verify that "username" is the right capitalization, as opposed to "userName". Unfortunately, incorrectly spelled/capitalized items don't get tagged as errors, since this is a generic XML being used by a generic interface.
The secret of how to be miserable is to constantly expect things are going to happen the way that they are "supposed" to happen.
You can have faith, which carries the understanding that you may be disappointed. Then there's being a willfully-blind idiot, which virtually guarantees it.