Strict Standards: Only variables should be assigned by reference PHP 5.4

It's because you're trying to assign an object by reference. Remove the ampersand and your script should work as intended.

You should remove the & (ampersand) symbol, so that line 4 will look like this:

$conn = ADONewConnection($config['db_type']);

This is because ADONewConnection already returns an object by reference. As per documentation, assigning the result of a reference to object by reference results in an E_DEPRECATED message as of PHP 5.3.0