if($PayPal->APICallSuccessful($PayPalResult['Ack']))
{
    // Write the contents of the response array to the screen for demo purposes.
    echo '<a href="' . $PayPalResult['RedirectURL'] . '">Click here to continue.</a><br /><br />';
}
else
{
    $PayPal->DisplayErrors($PayPalResult['Errors']);
}