php paypal class for express checkout

I'm using (trying to use) paypal class described here http://blog.moorberry.biz/2010/04/paypal-nvp-api/

However it doesn't seem to pass any data to paypal in my case. For example specifying

$paypal = new SetExpressCheckout("50.00"); 
$paypal->setNVP("ADDRESSOVERRIDE", 1);
$paypal->setNVP("NAME", "John");
$paypal->setNVP("SHIPTOSTREET", "Some Street");
$paypal->setNVP("SHIPTOCITY", "London");
$paypal->setNVP("SHIPTOCOUNTRY", "UK");
$paypal->getResponse();

doesn't affect paypal and when I logged in into it during the process, it defaults to Test User开发者_如何学Python 1 Main Street address. It also doesn't seem to pass AMT value correcty (current purchase stays empty)

If that class is proved to work wrong from any reason, can you provide an example of different class or code? I'm puzzled with this and cannot understand the whole process in 100%.