Paypal integration?

Hej Eksperter

Jeg prøver at lave et betalingssytem med paypal, men det virker ikke.

Jeg har en form, hvor brugeren selv kan bestemme, hvor mange penge, man vil sætte ind:

<form action="https://www.paypal.com/cgi-bin/webscr" method="post">
   
    <input type="hidden" name="cmd" value="_xclick">
    <input type="hidden" name="business" value="jgg@live.dk">

    Kroner <input type="text" name="amount">
     
    <input type="hidden" name="no_shipping" value="0">
    <input type="hidden" name="no_note" value="1">
    <input type="hidden" name="currency_code" value="DKK">
    <input type="hidden" name="lc" value="AU">
    <input type="hidden" name="bn" value="PP-BuyNowBF">

    <input type="hidden" name="email" value="<?php echo Session::get('bruger_email'); ?>">
    <input type="hidden" name="navn" value="<?php echo Session::get('bruger_navn'); ?>">
    <input type="hidden" name="brugernavn" value="<?php echo Session::get('bruger_brugernavn'); ?>">
    <input type="hidden" name="brugerid" value="<?php echo Session::get('bruger_id'); ?>">
    <input type="hidden" name="brugerefternavn" value="<?php echo Session::get('bruger_efternavn'); ?>">

    <input type="hidden" name="return" value="http://www.cc.com/partner/payment_complete">


    <br />
    <input type="submit" class="submit" value="Pay with PayPal!">


Jeg har så sat url min ipn url inde i paypal, som skal køre dette sript:

        // STEP 1: Read POST data
        // reading posted data from directly from $_POST causes serialization
        // issues with array data in POST
        // reading raw POST data from input stream instead.
        $raw_post_data = file_get_contents('php://input');
        $raw_post_array = explode('&', $raw_post_data);
        $myPost = array();
        foreach ($raw_post_array as $keyval) {
          $keyval = explode ('=', $keyval);
          if (count($keyval) == 2)
            $myPost[$keyval[0]] = urldecode($keyval[1]);
        }
        // read the post from PayPal system and add 'cmd'
        $req = 'cmd=_notify-validate';
        if(function_exists('get_magic_quotes_gpc')) {
          $get_magic_quotes_exists = true;
        }
        foreach ($myPost as $key => $value) {       
          if($get_magic_quotes_exists == true && get_magic_quotes_gpc() == 1) {
                $value = urlencode(stripslashes($value));
          } else {
                $value = urlencode($value);
          }
          $req .= "&$key=$value";
        }
       
       
        // STEP 2: Post IPN data back to paypal to validate
       
        $ch = curl_init('https://www.paypal.com/cgi-bin/webscr');
        curl_setopt($ch, CURLOPT_HTTP_VERSION, CURL_HTTP_VERSION_1_1);
        curl_setopt($ch, CURLOPT_POST, 1);
        curl_setopt($ch, CURLOPT_RETURNTRANSFER,1);
        curl_setopt($ch, CURLOPT_POSTFIELDS, $req);
        curl_setopt($ch, CURLOPT_SSL_VERIFYPEER, 1);
        curl_setopt($ch, CURLOPT_SSL_VERIFYHOST, 2);
        curl_setopt($ch, CURLOPT_FORBID_REUSE, 1);
        curl_setopt($ch, CURLOPT_HTTPHEADER, array('Connection: Close'));
       
        // In wamp like environments that do not come bundled with root authority certificates,
        // please download 'cacert.pem' from "http://curl.haxx.se/docs/caextract.html" and set the directory path
        // of the certificate as shown below.
        // curl_setopt($ch, CURLOPT_CAINFO, dirname(__FILE__) . '/cacert.pem');
        if( !($res = curl_exec($ch)) ) {
            // error_log("Got " . curl_error($ch) . " when processing IPN data");
            curl_close($ch);
            exit;
        }
        curl_close($ch);
       
       
        // STEP 3: Inspect IPN validation result and act accordingly
       
        if (strcmp ($res, "VERIFIED") == 0) {
            // check whether the payment_status is Completed
            // check that txn_id has not been previously processed
            // check that receiver_email is your Primary PayPal email
            // check that payment_amount/payment_currency are correct
            // process payment
            // assign posted variables to local variables
            $item_name                     = $_POST['item_name'];
            $item_number                 = $_POST['item_number'];
            $payment_status             = $_POST['payment_status'];
            $payment_amount             = $_POST['amount'];
            $payment_currency             = $_POST['currency_code'];
            $txn_id                     = $_POST['txn_id'];
            $receiver_email             = $_POST['business'];
            $payer_email                 = $_POST['email'];
            $bruger_email                     = $_POST['email'];
            $bruger_navn                     = $_POST['navn'];
            $brugernavn                     = $_POST['brugernavn'];
            $brugerid                         = $_POST['brugerid'];
            $brugerefternavn                 = $_POST['efternavn'];
            $date                             = date("Y-m-d H:i:s"); 

            $this->db->insert('partner_indbetalinger', array(
                  'indbetaling_sum'              => $payment_amount,
                'indbetaling_date'          => $date,
                'indbetaling_by'            => $brugerid,
            ));

        } else if (strcmp ($res, "INVALID") == 0) {
            // log for manual investigation
       
        }
    }

Paypals eget startsscript, som jeg har taget udgangspunkt i.

hvad gør jeg forkert, har prøvet at teste det med sandbox?