logout หน้าที่มีการเช็คค่าต่างๆไม่ได้นะค่ะ รบกวนช่วยดูโค้ดให้ทีนะค่ะ

 protected void done_Click(object sender, EventArgs e)
        {
            try
            {
                SqlConnection Conn = new SqlConnection(WebConfigurationManager.ConnectionStrings["InsuranceConnectionString"].ConnectionString);
                Conn.Open();

                string str = "INSERT INTO Customer (name, surname, tel, mobile, birthday, age, address, Employee_id) VALUES ('" + this.name.Text.Trim() + "','" + this.surename.Text.Trim() + "','" + this.tel.Text.Trim() + "','" + this.mobile.Text.Trim() + "','" + this.birthday.Text.Trim() + "','" + this.ages.Text.Trim() + "','" + this.address.Text.Trim() + "','" + Session["Employee_id"] + "')";
                SqlCommand myCommand = new SqlCommand(str, Conn);
                myCommand.ExecuteNonQuery();
                this.lbladdcustomer.Visible = true;
                
            }catch(ArgumentOutOfRangeException){
                errorage.ForeColor = System.Drawing.Color.Red;
                errorage.Text = "error:please insert birthday in a right format";
                errorage.Visible = true;
            }
            
        }
        protected void btnlogout_Click(object sender, EventArgs e)
        {
            if (Session["Employee_id"] != null)
            {
                Response.Redirect("/etc/logout.aspx");
            }
        }


<div id="columnleft">
    <div class="leftblock">
    
    <h2>Welcome</h2>
    <div class="dashedline"></div>
    <br />
    
                        <asp:Label ID="lblfullname" runat="server" Text="Label"></asp:Label>
                        <br />
                        <asp:Label ID="lblposition" runat="server" Text="Label"></asp:Label>
                        <br />
                        <br />
                        <asp:Button ID="btnlogout" runat="server" onclick="btnlogout_Click" 
                            Text="logout" />
    </div>
 </div>
<div id="maincolumn">
  <div class="mainblock">
  เพิ่มข้อมูลลูกค้า
    <div class="dashedline"></div>
    <table>
        <tr>
            <td>
                ชื่อ
                <asp:TextBox ID="name" runat="server" Width="100px"></asp:TextBox>
                <br />
                <asp:RequiredFieldValidator ID="RequiredFieldValidator1" runat="server" 
                    ControlToValidate="name" ErrorMessage="กรุณาใส่ชื่อ"></asp:RequiredFieldValidator>
            </td>
            <td>
...
</div>
</div>