Having trouble installing 2.7 (Error estabalishing a db connection)

I’m trying to install 2.7 onto my host and I keep getting the error “Error establishing a database connection”.

I’ve used a test.php to connect and select the DB and have tried successfully. However, when using the same exact combination of host, username, pass, db, etc.. it keeps feeding me the error.

I’ve verified that my host uses the latest versions of mysql and php. Is there any other areas I can check to debug this?