提交留言一直显示系统错误 是什么原因啊

就是后台创建了一个网站表单

            {php extract(dr_get_form_post_value('wzly'))}
                <form class="dinggou" onsubmit="return submsg(this);" action="" method="post" myform" id="myform">
                {$form}
                    <input type="text" name="data[title]" required="" id="contacts" class="form-control" placeholder="请输入联系人">
                    <input type="text" name="data[shouji]" required="" id="mobile" class="form-control" placeholder="请输入联系人手机">
                    <textarea name="data[neirong]" id="content" class="form-controltxt" placeholder="请输入留言内容"></textarea>
                    {if $is_post_code}
                    <div id="yanzm">
                        <input type="text" name="code" required="" id="checkcode" class="form-control" placeholder="请输入验证码">
                        <img title="点击刷新" src="{dr_code(120, 35)}">
                    </div>
                    {/if}
<button type="button" onclick="dr_ajax_submit('{dr_now_url()}', 'myform', '2000', '{$rt_url}')" class="btn green"> <i class="fa fa-save"></i> 提交内容</button>
</form>
                        <script>
                            function dr_liuyan() {
                                $.ajax({
                                    type: "POST",
                                    dataType: "json",
                                    data: $("#dr_liuyan").serialize(),
                                    url: "{dr_url('index.php?c=liuyan')}",
                                    success: function(json) {
                                        if (json.code) {
                                            layer.msg(json.msg);
                                        } else {
                                            layer.msg(json.msg);
                                        }
                                    },
                                    error: function(HttpRequest, ajaxOptions, thrownError) {
                                        // alert(HttpRequest.responseText);
                                        layer.msg('发生异常');
                                    }
                                });
                            }
                        </script>
            </div>