Unable to Get Element with ID in VB.Net - asp.net

Question

I have the below code to retrieve the table element when the checkbox is checked.
With this, I could get the table ID. When I try to get the HtmlTable with the ID, it throws the null reference exception.
Once I get the table element with its ID, I need to loop through the rows of that table. Could anyone help me out?
ASPX.VB
Protected Sub CheckBox2_CheckedChanged(sender As Object, e As EventArgs)
Dim tab As String
Dim check As CheckBox = CType(sender, CheckBox)
tab = check.Parent.Parent.Parent.ID
Dim tabb As HtmlControl = Me.FindControl(tab)
Dim myTab As HtmlTable = CType(tabb, HtmlTable)
For Each cell As HtmlTableRow In myTab.Rows
//My Code Here
Next
End Sub
ASPX:
<table id="itemlist" class="mel-table" runat="server">
<tr>
<td>
<asp:CheckBox runat="server" ID="CheckBox2" OnCheckedChanged="CheckBox2_CheckedChanged" AutoPostBack="true" />
</td>
</tr>
</table>

Answer 1

Use the parent element ID under which the table is nested like below.
Protected Sub CheckBox2_CheckedChanged(sender As Object, e As EventArgs)
Dim tab As String
Dim check As CheckBox = CType(sender, CheckBox)
tab = check.Parent.Parent.Parent.ID
Dim myTab As HtmlTable = CType(mydiv.FindControl(tab), HtmlTable)
For Each cell As HtmlTableRow In myTab.Rows
//My Code Here
Next
End Sub
<div id="mydiv" runat="server">
<table id="itemlist" class="mel-table" runat="server">
<tr>
<td>
<asp:CheckBox runat="server" ID="CheckBox2" OnCheckedChanged="CheckBox2_CheckedChanged" AutoPostBack="true" />
</td>
</tr>
</table>
</div>