Why can't I make a TH runat=“server”

Question

For ASP.Net, I know I can make a lot of different HTML elements runat="server" so I can do specific things to it from the server, but I'm not able to get a TH to runat="server".

Why not?

example:

<table>
<tr>
<td id="tdMyCell" runat="server"></td>
<th id="thMyCell" runat="server"></th>
</tr>
</table>

but from server side, I'm only able to access the TD. I've tried to two lines below, the first won't compile and the second always returns a null object.

thMyCell.Visible = false;
(this.FindControl("thMyCell") as System.Web.UI.HtmlControls.HtmlTableCell).Visible = false;

Update:

My fault, I copied something and I didn't change it before I posted... it's been fixed in the code

Answer 1

This might be a forehead slapper, but:

Because your th is called "thMyCell", not "thLastColumn"

Answer 2

If your implementation is as straight forward as your example, you should have a problem with this. It doesn't give me any issues, and compiles without any errors.

<table>
    <tr>
        <th id="test" runat="server"></th>
    </tr>
</table> 

In the code-behind intellisense picks it up as an HtmlTableCell , but that shouldn't be a problem:

test.ColSpan = 2;

If this isn't working for you, I would try to isolate it - create a new web form and paste in the markup I have above, then try to access it in the code-behind. Intellisense should pick it up without a problem, and the form should compile just fine.