我正在创建发票表单，给了我500个未定义的索引错误

我正在创建发票表单，它从两个模型Invoice和InvoiceDetails中检索数据当我提交表格时，它会给我

错误500：未定义的索引：站点名称。

public function actionCreate()
{
    $model=new Invoice;
    $detail = new InvoiceDetail();
    if(isset($_POST['Invoice']))
    {
        $model->attributes=$_POST['Invoice'];
            if(isset($_POST['InvoiceDetail'])){
                $detail = $_POST['InvoiceDetail'];
                foreach($detail as $key=>$details){
                    $det = new InvoiceDetail();
                    $det->attributes = array(
                        'invoice_id' => $model->id,
                        'site_name' => $detail['site_name'][$key],
                        'do_number' => $detail['do_number'][$key],
                        'description' => $detail['description'][$key],
                        'quantity' => $detail['quantity'][$key],
                        'rate' => $detail['rate'][$key],
                        'amount' => isset($detail['amount'][$key])?$detail['amount'][$key]:NULL,
                    );
                    $det->save(false);
                }
            }

        }

    $this->layout='columnInvoice';
    $this->render('create',array(
        'model'=>$model,
        'detail' => $detail
    ));
}