php - 支付宝支付错误返回ILLEGAL_SIGN，签名验证错误

用的是ECSHOP商城框架，在本地测试（windows系统）的时候，正常交易。但到了生产环境（Centos系统）后，支付宝就会报ILLEGAL_SIGN（签名验证错误）错误。网上看过一些解决方法，但都没作用。下面是生成支付宝支付代码的代码：

    function get_code($order, $payment)
    {
        if (!defined('EC_CHARSET'))
        {
            $charset = 'utf-8';
        }
        else
        {
            $charset = EC_CHARSET;
        }

        $real_method = $payment['alipay_pay_method'];

        switch ($real_method){
            case '0':
                $service = 'trade_create_by_buyer';
                break;
            case '1':
                $service = 'create_partner_trade_by_buyer';
                break;
            case '2':
                $service = 'create_direct_pay_by_user';
                break;
        }


        $parameter = array(
            'agent'             => $payment['alipay_agent'],
            'service'           => $service,
            'partner'           => $payment['alipay_partner'],
            //'partner'           => ALIPAY_ID,
            '_input_charset'    => $charset,
            'notify_url'        => return_url(basename(__FILE__, '.php')),
            'return_url'        => return_url(basename(__FILE__, '.php')),
            /* 业务参数 */
            'subject'           => $order['order_sn'],
            'out_trade_no'      => $order['order_sn'] . $order['log_id'],
            'extra_common_param'=> !empty($order['all_pay'])?$order['all_pay']:0, //判断是不是合并付款 add by ouzhiming
            'price'             => $order['order_amount'],
            'quantity'          => 1,
            'payment_type'      => 1,
            /* 物流参数 */
            'logistics_type'    => 'EXPRESS',
            'logistics_fee'     => 0,
            'logistics_payment' => 'BUYER_PAY_AFTER_RECEIVE',
            /* 买卖双方信息 */
            'seller_email'      => $payment['alipay_account']
        );

        ksort($parameter);
        reset($parameter);

        $param = '';
        $sign  = '';

        foreach ($parameter AS $key => $val)
        {
            $param .= "$key=" .urlencode($val). "&";
            $sign  .= "$key=$val&";
        }

        $param = substr($param, 0, -1);
        $sign  = substr($sign, 0, -1).$payment['alipay_key'];
        //$sign  = substr($sign, 0, -1). ALIPAY_AUTH;

        $button = '
';

        return $button;
    }