Database connect problem

[gina4h]

I installed the catalog on my computer and all went well so I tried to install on-lineover an older corrupt version of osCommerce (somebody thought it was like playing with html). Everything appeared to go smoothly, I initially had some problems with the admin files but have been able to fix those, but when I go to the home page I get

"Unable to connect to database server!" error and nothing else.

 

Please help!

[Avec]

1. Does the database exist?

2. Is it where you think it is?

3. Are your configure.php files (both of them) correct in this regard? Some servers name their databases a concatonated name consisting of your host user ID~database name, same goes for database user ID