Error establishing a database connection

I keep having trouble logging in to my new blog. I’ve checked everything several times and I continue to get the “Error establishing a database connection” — and I can’t figure out why. I’ve installed blogs before so I don’t know what is different this time.

I can go to the main domain and a listing of all my sub-domains show (I don’t have anything on the main domain), so it seems that probable eliminates the server being down. I’ve double and triple checked my names/passwords. Any ideas?

Thanks for your help.