MongoVUE connect to mongodb with authencation failed!
Your error looks like a standard "auth failed" exception... If all the parameters of your connection are correct for your setup, I'd suggest you try to logon from the mongo shell directly:

$&gt;mongo 1.2.3.4:40000/genbank  -u genBankReader -p passwd1234 --authenticationDatabase admin --verbose

Use the --verbose flag to log on as both the "read-only" user and the "admin" user and see if you can tell more of what's wrong (if any).

Alternative you can use another mongo client GUI like Robomongo and see if that works.
(I used to use MongoVue but switched to Robomongo as it was less confusing and more shell-oriented)

Otherwise, you could have setup/added the users incorrectly. Use the admin user to check db.system.users collection of the proper database just to make sure. Perhaps take another look at http://docs.mongodb.org/manual/reference/privilege-documents/ 

Hope this helps, good luck