Update command can't find the correct value of the control

Question

This is small example what i tried

protected void Page_Load(object sender, EventArgs e)
{
  if (!Page.IsPostBack) {
       bindgv();
  }
}

public void bindgv()
{
  SqlDataAdapter dap = new SqlDataAdapter("select * from mytable", Con);
  DataSet ds = new DataSet();
  dap.Fill(ds);
  GridView1.DataSource = ds.Tables[0];
  GridView1.DataBind();
}

protected void GridView1_RowUpdating(object sender, GridViewUpdateEventArgs e)
{
  GridViewRow row = (GridViewRow)GridView1.Rows[e.RowIndex];
  CheckBox c1 = (CheckBox)GridView1.Rows[e.RowIndex].FindControl("CheckBox1");
  CheckBox c2 = (CheckBox)GridView1.Rows[e.RowIndex].FindControl("CheckBox2");
  CheckBox c3 = (CheckBox)GridView1.Rows[e.RowIndex].FindControl("CheckBox3");
  Label lblid = (Label)GridView1.Rows[e.RowIndex].FindControl("lblid");
  updateMethod(lblid.Text, c1.Checked, c2.Checked, c3.Checked);

}

public void updateMethod(string id, bool c1, bool c2, bool c3)
{
  using (SqlConnection con = new SqlConnection(myCon))
  {
     con.Open();
     SqlCommand cmd = new SqlCommand("update mytable set c1= @c1value , c2=@c2value, c3= @c3value where id=@id", con);
     cmd.Parameters.AddWithValue("@c1value", c1);
     cmd.Parameters.AddWithValue("@c2value", c2);
     cmd.Parameters.AddWithValue("@c3value", c3);
     cmd.Parameters.AddWithValue("@id", id);
     cmd.ExecuteNonQuery();
  }
    GridView1.EditIndex = -1;
    bindgv();
}

protected void GridView1_RowEditing(object sender, GridViewEditEventArgs e)
{
  GridView1.EditIndex = e.NewEditIndex;
  bindgv();
}

protected void GridView1_RowCancelingEdit(object sender, GridViewCancelEditEventArgs e)
{
  GridView1.EditIndex = -1;
  bindgv();
}

HTML MarkUp

<asp:GridView ID="GridView1" runat="server" AutoGenerateColumns="False" 
onrowediting="GridView1_RowEditing" 
onrowcancelingedit="GridView1_RowCancelingEdit" 
onrowupdating="GridView1_RowUpdating">
<Columns>
    <asp:TemplateField HeaderText="ID">
        <ItemTemplate>
            <asp:Label ID="lblid" runat="server" Text='<%# Bind("id") %>'></asp:Label>
        </ItemTemplate>

    </asp:TemplateField>
    <asp:TemplateField HeaderText="Name">
        <ItemTemplate>
            <asp:Label ID="Label3" runat="server" Text='<%# Bind("name") %>'></asp:Label>
        </ItemTemplate>
    </asp:TemplateField>
    <asp:TemplateField HeaderText="checkbox">
    <ItemTemplate>
    <table>
    <tr>   
    <td><asp:Label ID="Label2" runat="server" Text='<%# Bind("c1") %>'></asp:Label></td>
    <td><asp:Label ID="Label5" runat="server" Text='<%# Bind("c2") %>'></asp:Label></td>
    <td><asp:Label ID="Label4" runat="server" Text='<%# Bind("c3") %>'></asp:Label></td>
    </tr>
     <tr>  
     <td> <asp:CheckBox ID="CheckBox1" runat="server" Checked='<%# Bind("c1") %>' /></td>
     <td><asp:CheckBox ID="CheckBox2" runat="server" Checked='<%# Bind("c2") %>' /></td>
     <td><asp:CheckBox ID="CheckBox3" runat="server" Checked='<%# Bind("c3") %>' /></td>
     </tr>
    </table>
   </ItemTemplate>
 <EditItemTemplate>
   <table>
    <tr>   
    <td><asp:Label ID="Label2" runat="server" Text='<%# Bind("c1") %>'></asp:Label></td>
    <td><asp:Label ID="Label5" runat="server" Text='<%# Bind("c2") %>'></asp:Label></td>
    <td><asp:Label ID="Label4" runat="server" Text='<%# Bind("c3") %>'></asp:Label></td>
   </tr>
   <tr>  
    <td> <asp:CheckBox ID="CheckBox1" runat="server" Checked='<%# Bind("c1") %>' /></td>
    <td><asp:CheckBox ID="CheckBox2" runat="server" Checked='<%# Bind("c2") %>' /></td>
    <td><asp:CheckBox ID="CheckBox3" runat="server" Checked='<%# Bind("c3") %>' /></td>
  </tr>
   </table>
        </EditItemTemplate>
    </asp:TemplateField>
    <asp:TemplateField ShowHeader="False">
        <ItemTemplate>
            <asp:LinkButton ID="LinkButton1" runat="server" CausesValidation="False" 
                CommandName="Edit" Text="Edit"></asp:LinkButton>
        </ItemTemplate>
        <EditItemTemplate>
            <asp:LinkButton ID="LinkButton1" runat="server" CausesValidation="True" 
                CommandName="Update" Text="Update"></asp:LinkButton>
            &nbsp;<asp:LinkButton ID="LinkButton2" runat="server" CausesValidation="False" 
                CommandName="Cancel" Text="Cancel"></asp:LinkButton>
        </EditItemTemplate>
    </asp:TemplateField>
</Columns>
</asp:GridView>

ScreenShot:

ScreenShot