the famous Multisite 'Error establishing a database connection' error

Hi there,

I've looked almost everywhere but I can't figure out what's going wrong here.
I've setup the multisite. Choose for subdomain.
And when creating a new site, I'll get this error.

The strange thing here, is that if I look in the DB there's just a new site created.
So the DB connection is working....

And that's why I don't understand and figure out this error...

The DB server is running well, the details are correct,...
Somebody any idea?

Big thanx!