cURL返回通用错误500

Question

I try to create to create my ExpressCheckout but my code return me an error 500.

Here is the code :

$ch = curl_init($requete);

curl_setopt($ch, CURLOPT_RETURNTRANSFER, TRUE);
curl_setopt($ch, CURLOPT_SSL_VERIFYHOST, FALSE);
curl_setopt($ch, CURLOPT_SSL_VERIFYPEER, FALSE);

$resultat_paypal = curl_exec($ch);


if (!$resultat_paypal)
    {echo "<p>Erreur</p><p>".curl_error($ch)."</p>";}
else
{
    $liste_param_paypal = recup_param_paypal($resultat_paypal); 

    if ($liste_param_paypal['ACK'] == 'Success')
    {

        header("Location: https://www.sandbox.paypal.com/webscr&cmd=_express-checkout&token=".$liste_param_paypal['TOKEN']);
        exit();
    }
    else
    {echo "<p>Erreur de communication avec le serveur PayPal.<br />".$liste_param_paypal['L_SHORTMESSAGE0']."<br />".$liste_param_paypal['L_LONGMESSAGE0']."</p>";}

I also tried :

curl_exec($ch) === false instead if (!$resultat_paypal)