将html无序列表值传递给c#文本框并在sqlquery中使用

这是我用来将文本设置为特定值的javascript

document.getElementById('Original Map').addEventListener('click', function () {
    map.setView([52.42922, -18.5154], 5);
    var text = document.getElementById("mytext");
    text.value = "Original Map";
});

这是html

<form id="Form1" runat="server" >
    <ul>
        <li> 
            <li><label><h5>Now Selected: </h5></label>
            <asp:TextBox ID="mytext" runat="server" ReadOnly style=" font-size:15px;  border:0px; " BackColor="White" ForeColor="#6699FF"></asp:TextBox></li>
            <li><asp:Button ID="Button2" runat="server" Text="Button" style ="border-radius:5px; width:100px; padding:5px;" class="btn btn-primary" OnClick="Button1_click" /></li> 
        </li>
    </ul>
    <asp:GridView ID="GridView1" runat="server" BackColor="White" AlternatingRowStyle-BackColor="Black" BorderColor="White">
    </asp:GridView>
</form> 

这是c#代码

OleDbConnection con = new OleDbConnection(@"Provider=Microsoft.ACE.OLEDB.12.0;Data Source=C:'Users'mduggan'Documents'Database1.accdb");
public string TextBoxValue
{
    get { return mytext.Text; }
    set { mytext.Text = value; }
}   
protected void Button1_click(object sender, EventArgs e)
{
    filldata();
}
protected void filldata()
{
    string query;
    query = TextBoxValue;
    if (query != null)
    {
        con.Open();
        string str = "SELECT PageID, PageName FROM Maps WHERE PageName ='" + query + "'";
        OleDbCommand cmd = new OleDbCommand(str, con);
        OleDbDataReader dr = cmd.ExecuteReader();
        GridView1.DataSource = dr;
        GridView1.DataBind();
    }
    else 
    {
        Label1.Visible = true;
    }
}

为什么查询变量(在。cs类中)不从HTML无序列表中拾取TextBoxValue值。

列表中的值被转移到文本框中，但是随后查询变量没有检测到文本框中的任何值，并且在返回的sqlquery