无法显示MPDF中所有变量的总和

Question

我使用PDF来显示PDF格式的数据。我从3个表中获取数据。所有表都有不同的金额和总和，所以我将每个表总和存储在一个变量中。在表的末尾我总结所有这些变量并试图显示，但它没有显示表页脚中的任何总和，如果我删除PDF代码并将页面转换为HTML所有工作正常。这是代码。

<table class="items" width="100%" style="font-size: 9pt; border-collapse: collapse; " cellpadding="8">
        <thead>
            <tr>
                <td> Sr. No </td>
                <td> Date </td>
                <td> Branch / Bank </td>
                <td> Reciever Name </td>
                <td> Father Name </td>
                <td> Reciever Number </td>
                <td> Amount (AED) </td>
                <td> Amount (Pkr) </td>
            </tr>
        </thead>
        <tbody>';
            $sum_open = 0; $sum_Pkr = 0; $counter = 1; 
            foreach($open_orders as $open_order) {
            $html .= '<tr>
                <td> '.$counter++.' </td>
                <td> '.$open_order -> order_date.' </td>
                <td> '.$open_order -> branch_Name.' </td>
                <td> '.$open_order -> r_name.' </td>
                <td> '.$open_order -> r_father.' </td>
                <td> '.$open_order -> r_number.' </td>
                <td> '.$open_order -> amount_aed.' </td>
                <td> '.$open_order -> amount_pkr.' </td>
                '.$sum_open += $open_order -> amount_aed.'
                '.$sum_Pkr += $open_order -> amount_pkr.'
            </tr>';
            }
            $sum_bank_AED = 0; $sum_bank_Pkr = 0; $counter = 1;
            foreach ($bank_orders as $bank_order) {
            $html .= '<tr>
                <td> '.$counter++.' </td>
                <td> '.$bank_order -> Order_Date.' </td>
                <td> '.$bank_order -> bank_name.' Bank </td>
                <td> '.$bank_order -> r_name.' </td>
                <td> '.$bank_order -> r_fname.' </td>
                <td> '.$bank_order -> r_number.' </td>
                <td> '.$bank_order -> amount.' </td>
                <td> '.$bank_order -> amount_pkr.' </td>
                '.$sum_bank_AED += $bank_order -> amount.'
                '.$sum_bank_Pkr += $bank_order -> amount_pkr.'
            </tr>';
            }
            $sum_deposit_AED = 0; $sum_deposit_Pkr = 0; $counter = 1;
            foreach ($deposit_orders as $deposit_order) {
            $html .= '<tr>
                <td> '.$counter++.' </td>
                <td> '.$deposit_order -> depositDate.' </td>
                <td> '.$deposit_order -> branch_Name.' </td>
                <td> '.$deposit_order -> name.' </td>
                <td> '.$deposit_order -> r_name.' </td>
                <td> '.$deposit_order -> r_number.' </td>
                <td> '.$deposit_order -> amount_aed.' </td>
                <td> '.$deposit_order -> amount_pkr.' </td>
                '.$sum_deposit_AED += $deposit_order -> amount_aed.'
                '.$sum_deposit_Pkr += $deposit_order -> amount_pkr.'
            </tr>';
        }
        $html .= '</tbody>
        <tfoot>
            <tr>
                <td></td>
                <td></td>
                <td></td>
                <td></td>
                <td></td>
                <td></td>
                <td>'.$sum_open + $sum_bank_AED + $sum_deposit_AED.'/- AED</td>
                <td>'.$sum_Pkr + $sum_bank_Pkr + $sum_deposit_Pkr.'/- Pkr</td>
            </tr>
        </tfoot>
    </table>

表格页脚的输出应该是这样的