I did have very similar problem jusour ago:-). I did move my Joomla 1.0.15 site from another hosting to here.
I have created SQL database, with the user of course, then imported backup files to it using PHPMy Admin.
The verdict was; This site is not working, contact your administrator, could not connect to database server.
Well, I have deleted the database and user. Even reuploaded public_html folder. Then created everything again. The result was the same.
And...I admitted my stupidness, cause I didn't change "localhost" to the actual name of my SQl server at 000webhost.
I did it manually in configuration.php
In my case it was:
$mosConfig_host = 'localhost';
$mosConfig_host = 'mysql1.000webhost.com';
and...Bob's your uncle!