paypal express test

hi Andreas,
i try to test the paypal express, i have copy the folder to my server, i have set my username - pass - and sign but it looks that the script stuck after this

$gateway = new PaypalExpress(
array(
'login' => PAYPAL_LOGIN,
'password' => PAYPAL_PASS,
'signature' => PAYPAL_SIG,
'currency' => 'USD'
)
);