Changing PDO connection method doesn't work

[rosoonline]

If I change the code in the import example from:

$pdo = new PDO('mysql:host=localhost;dbname=test', 'root', 'root');

to

$pdo = DB::connection()->getPdo();

Why does the import stop working? I don't get any error messages, the SQL just doesn't run. It's not a big issue as I've got it to use my DB settings by using:

$pdo = new PDO('mysql:host='.$_ENV['DB_HOST'].';dbname='.$_ENV['DB_DATABASE'], $_ENV['DB_USERNAME'], $_ENV['DB_PASSWORD']);

but this isn't as nice!