I have a asp:Panel element on my page. I'm able to set its visibility in code behind. But I need to also hide it through javascipt.

My panel is defined as following:

     <asp:Panel ID=pnlUpdateDisplay runat=server Visible=false style=width:500px; border-width: thick;>

        <table style=width:300px;>

            <tr>

                <td valign=middle style=width:120px align=center>

                <asp:Label ID=lblUpdateMessage runat=server style=position:absolute; left: 120px; top: 120px;></asp:Label>

                </td>

            </tr>

        </table>      

    </asp:Panel>

When I do this:

   var panel = document.getElementById('pnlUpdateDisplay');

   panel.style.visibility = 'hidden';

   panel.style.display='none';

There is an error saying: Error: Unable to get value of the property 'style': object is null or undefined

Any suggestions?