Dynamically generated checkbox gets removed when checkbox check is changed - asp.net

Question

I am dynamically generating checkbox on the basis of text entered in a textbox. When any of the checkbox is checked\unchecked, the checkbox gets removed. When I inspect element I cannot find checkbox and its change event is not fired. All these controls are in update panel.
Code is as follows:
<ajax:UpdatePanel ID="UpdatePanel2" runat="server" UpdateMode="Conditional">
<ContentTemplate>
<table>
<tr>
<td>
<asp:TextBox ID="txtProducts" runat="server" AutoPostBack="true" onblur="return validate();" OnTextChanged="txtProducts_TextChanged"></asp:TextBox>
</td></tr>
<tr>
<td>
<panel runat="server" id="panelDynamicCheckbox"></panel>
</td>
</tr>
</table>
</ContentTemplate>
<Triggers>
<ajax:AsyncPostBackTrigger ControlID="txtProducts" EventName="TextChanged" />
</Triggers>
</ajax:UpdatePanel>
Code Behind:
protected void txtProducts_TextChanged(object sender, EventArgs e)
{
string[] products = txtProducts.Text.Split(',');
CheckBox[] chk = new CheckBox[products.Length];
int countForCheckbox = 0;
foreach (string product in products)
{
chk[countForCheckbox] = new CheckBox();
chk[countForCheckbox].ID = product;
chk[countForCheckbox].Text = product;
chk[countForCheckbox].Checked = true;
chk[countForCheckbox].AutoPostBack = true;
chk[countForCheckbox].EnableViewState = true;
chk[countForCheckbox].CheckedChanged += new EventHandler(Dynamic_CheckChanged);
panelDynamicCheckbox.Controls.Add(chk[countForCheckbox]);
countForCheckbox++;
}
}
protected void Dynamic_CheckChanged(object sender, EventArgs e)
{
CheckBox checkbox = (CheckBox)sender;
lblProductDetails.Text = "Done";
}
On textchange it shows the checkboxes but when I uncheck checkbox is gets removed.

Answer 1

I got my answer.
On postback dynamically created elements get removed so on postback I have to generate elements again. So in page_load I did following:
protected void Page_Load(object sender, EventArgs e)
{
if (IsPostBack)
{
CheckBox[] chk = new CheckBox[products.Length];
int countForCheckbox = 0;
panelDynamicCheckbox.Controls.Clear();
foreach (string product in products)
{
chk[countForCheckbox] = new CheckBox();
chk[countForCheckbox].ID = product;
chk[countForCheckbox].Text = product;
chk[countForCheckbox].Checked = true;
chk[countForCheckbox].AutoPostBack = true;
chk[countForCheckbox].EnableViewState = true;
chk[countForCheckbox].CheckedChanged += new EventHandler(Dynamic_CheckChanged);
panelDynamicCheckbox.Controls.Add(chk[countForCheckbox]);
countForCheckbox++;
}
}
}