Paypal wrong url - Printable Version

PHP Code:
function  __construct() {
        parent::__construct();
        $this->load->helper('form');
        $this->load->helper('url');
        $this->load->library('paypal_lib');
        $this->load->model('product_model');
    }


    function index(){
        $data = array();
        //get products data from database
        $data['products'] = $this->product_model->getRows();
        $data['title'] = 'Products';
        //pass the products data to view
        $this->load->view('products', $data);
    }

    function buy($id){
        //Set variables for paypal form
        $paypalURL = 'https://www.sandbox.paypal.com/cgi-bin/webscr'; //test PayPal api url
        $paypalID = 'Here i am using my Paypal Business Email' ; //business email
        $returnURL = base_url().'paypal/success'; //payment success url
        $cancelURL = base_url().'paypal/cancel'; //payment cancel url
        $notifyURL = base_url().'paypal/ipn'; //ipn url
        //get particular product data
        $product = $this->product_model->getRows($id);
        $userID = 1; //current user id

        $this->paypal_lib->add_field('business', $paypalID);
        $this->paypal_lib->add_field('return', $returnURL);
        $this->paypal_lib->add_field('cancel_return', $cancelURL);
        $this->paypal_lib->add_field('notify_url', $notifyURL);
        $this->paypal_lib->add_field('item_name', $product['name']);
        $this->paypal_lib->add_field('custom', $userID);
        $this->paypal_lib->add_field('item_number',  $product['products_id']);
        $this->paypal_lib->add_field('amount',  $product['price']);        
        
        $this->paypal_lib->paypal_auto_form();
    }