Strict Standards: Only variables should be assigned by reference PHP 5.4
Solution 1:
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
Solution 2:
It's because you're trying to assign an object by reference. Remove the ampersand and your script should work as intended.