难以将标签值传递给列表视图

我要找的是获得"Label10"的值，这是进入viewmsgView，然后根据标签值绑定FormView1，注意:viewmsgView &FormView1位于同一视图和同一页面中。但我得到一个错误消息如下，我已经添加了查找控制，因为它给出的错误消息，控制不可用或不存在。

"对象引用未被设置为对象的实例"

RedMsgDAADP.SelectCommand.Parameters.AddWithValue("@mailno", ((Label)myControl).Text);

viewmsgView，其中包括Label10以及titlehyplink，当用户点击它将显示并绑定FormView1

<asp:ListView ID="viewmsgView" runat="server">
                        <ItemTemplate>

                        <div class="col-lg-12">
                        <table class="table table-inbox table-hover" style="width:100%; margin-left:0px;">
                    <tbody>
                    <tr class="unread">
                        <td>
                            <asp:ImageButton ID="deltimgbtn" runat="server" 
                                ImageUrl="~/iconsimg/Delete2.png" onclick="deltimgbtn_Click" /> </td>  <td>
                            <asp:ImageButton ID="ReplyBtn" runat="server" ImageUrl="~/iconsimg/reply.png" 
                                onclick="ReplyBtn_Click" /></td>
                        <td class="view-message  dont-show"><asp:Label ID="msgfromlbl" runat="server" Text='<%# Bind ("sender") %>'></asp:Label></td>
                        <td class="view-message "><asp:LinkButton
                                ID="titlehyplink" runat="server" Text='<%# Bind ("Mestitle") %>' onclick="titlehyplink_Click"></asp:LinkButton></td>
                        <td class="view-message  inbox-small-cells"><asp:Label ID="Label10" runat="server" Style="color: #FFFFFF" Text='<%# Bind ("mailno") %>'></asp:Label></td>
                        <td class="view-message  text-right"><asp:Label ID="datelbl" runat="server" Text='<%# Bind ("Date") %>'></asp:Label></td>
                    </tr></tbody></table>
                    </div>
                        </ItemTemplate>
                        </asp:ListView>

FormView1，它将根据Label10显示消息细节，Label10是viewmsgView

<asp:FormView ID="FormView1" runat="server"  Width="100%">
                        <ItemTemplate>

                     <br /><br />
                     <div style="margin-bottom:40px; background-color:#CCCCCC;">
                         <div class="col-md-4">
                                        <label>From:</label>
                                        &nbsp;
                                        <asp:Label ID="senderLabel" runat="server" Text='<%# Bind("sender") %>' />
                                    </div>
                                    <div class="col-md-4">
                                        <label>Date:</label>
                                        <asp:Label ID="DateLabel" runat="server" Text='<%# Bind("Date") %>' />
                                </div>
                                 <div class="col-md-4">
                                        <label>To:</label>
                                        &nbsp;<asp:Label ID="Label11" runat="server" Text='<%# Bind("Receiver") %>' />
                                    </div>
                                     <div class="col-md-4">
                                   <label>Mail No:</label>
                                    <asp:Label ID="Label15" runat="server" Text='<%# Eval("mailno") %>' />
                              </div>
                                 <div class="col-md-4">
                                        <label>Ads No:</label>
                                        &nbsp;&nbsp;<asp:Label ID="AdsIDLabel" runat="server" Text='<%# Bind("AdsID") %>' />
                                  </div>
                                   </div>
                            <br />
                            <br />
                            <asp:Label ID="MestitleLabel" runat="server" Text='<%# Bind("Mestitle") %>' Font-Bold="True"
                                Font-Size="Larger" /><br />
                            <br />
                            <asp:Label ID="MessageLabel" runat="server" Text='<%# Bind("Message") %>' Width="100%"
                                CssClass="labelmsg" />
                        </ItemTemplate>
                    </asp:FormView>

标题链接后面的代码

protected void titlehyplink_Click(object sender, EventArgs e)
    {
        if (Session["UsrNme"] != null)
        {
            using (SqlConnection RedMsgSQLCon = new SqlConnection(sc))
            {
                RedMsgSQLCon.Open();
                SqlDataAdapter RedMsgDAADP = new SqlDataAdapter(@"SELECT * From mails where Receiver=@UID And mailno=@mailno", sc);
                var use = Session["UsrNme"];
                Control myControl = FindControl("Label10");
                RedMsgDAADP.SelectCommand.Parameters.AddWithValue("@UID", use);
                RedMsgDAADP.SelectCommand.Parameters.AddWithValue("@mailno", ((Label)myControl).Text);
                DataSet RedMsgCVs = new DataSet();
                RedMsgDAADP.Fill(RedMsgCVs);
                FormView1.DataSource = RedMsgCVs.Tables[0];
                FormView1.DataBind();
                FormView1.Visible = true;
            }
        }
        else
        {
        }
    }

<asp:LinkButton ID="titlehyplink" runat="server" Text='<%# Bind ("Mestitle") %>' onclick="titlehyplink_Click"></asp:LinkButton>

<asp:LinkButton ID="titlehyplink" runat="server" Text='<%# Bind "Mestitle") %>' CommandArgument='<%# Bind ("mailno") %>' OnCommand="titlehyplink_Command"></asp:LinkButton>

protected void titlehyplink_Click(object sender, EventArgs e)

protected void titlehyplink_Command(object sender, CommandEventArgs e)

RedMsgDAADP.SelectCommand.Parameters.AddWithValue("@mailno", e.CommandArgument);