I have a gridview, and I made a template column with a checkbox inside.
Then I want to check the value of checkboxes.
I'm trying to set the row's visible property to `false` when that row's checkbox is unselected.
I'm always getting `null`, no matter what I do.

It must be a problem with the `FindControl()`, but I think it is perfectly normal:

```
public partial class _Default : System.Web.UI.Page 
{
    protected void Page_Load(object sender, EventArgs e)
    {
        DbInteract dbi = new DbInteract("CONNECTION STRING");
        GridView1.DataSource = dbi.SqlDA("select * from table");
        GridView1.DataBind();
    }
    protected void ProsseguirBtn_Click(object sender, EventArgs e)
    {
        if (!IsPostBack)
        {
            foreach (GridViewRow row in GridView1.Rows)
            {
                CheckBox cb = (CheckBox)row.FindControl("chk");
                if (!cb.Checked)
                {
                    GridView1.Rows[row.RowIndex].Visible = false;
                }
            }
        }
    }
}

```

---

```
<%@ Page Language="C#" AutoEventWireup="true"  CodeFile="Default.aspx.cs" Inherits="_Default" %>

<!DOCTYPE html PUBLIC "-//W3C//DTD XHTML 1.0 Transitional//EN" "http://www.w3.org/TR/xhtml1/DTD/xhtml1-transitional.dtd">

<html xmlns="http://www.w3.org/1999/xhtml">
<head runat="server">
    <title></title>
</head>
<body>
    <form id="form1" runat="server">
    <div>

        <asp:GridView ID="GridView1" runat="server" AutoGenerateColumns="False">
            <Columns>
                <asp:TemplateField>
                    <EditItemTemplate>
                        <asp:TextBox ID="TextBox1" runat="server"></asp:TextBox>
                    </EditItemTemplate>
                    <ItemTemplate>
                        <asp:CheckBox ID="chk" runat="server" />
                    </ItemTemplate>
                </asp:TemplateField>
                <asp:BoundField DataField="nome" HeaderText="jhf" />
            </Columns>
        </asp:GridView>
        <asp:Button ID="ProsseguirBtn" runat="server" Text="Button" 
            onclick="ProsseguirBtn_Click" />

        <asp:TextBox ID="TextBox1" runat="server"></asp:TextBox>

    </div>
    </form>
</body>
</html>

```