Set td to False

[sonia.sardana]

I wnat to make td to false and true on the master Page Load.

public partial class Templates_Deloitte : System.Web.UI.MasterPage
{
    private bool m_LeftNavVisible = true;
    protected void Page_Load(object sender, EventArgs e)
    {

        this.tdTree1.Visible = NavVisible;
        this.divTree1.Visible = NavVisible;

    }

    public bool NavVisible
    {

        get
        {

            return this.m_LeftNavVisible;

        }

        set
        {

            this.m_LeftNavVisible = value;

        }
    }

SOURCE CODE--

<div id="divContent">
        <table width="100%" cellpadding="0" cellspacing="0" border="0">
            <tr>
                <td runat="server" id="tdTree1" style="vertical-align: top; width: 0%; text-align: left;">
                    <div runat="server" id="divTree1" style="width: 250px; height: 600px; overflow: auto;
                        padding: 0px; margin: 0px;" class="gradient">
                                            </div>
                </td>
                           </tr>
        </table>
    </div>

I am getting the error
'Templates_Deloitte' does not contain a definition for 'tdTree1' and no extension method 'tdTree1' accepting a first argument of type 'Templates_Deloitte' could be found (are you missing a using directive or an assembly reference?)

When I run the Page & view source then

 <div id="divContent">
        <table width="100%" cellpadding="0" cellspacing="0" border="0">
            <tr>
                <td id="ctl00_tdTree1" style="vertical-align: top; width: 0%; text-align: left;">
                    <div id="ctl00_divTree1" style="width: 250px; height: 400px; overflow: auto;
                        padding: 0px; margin: 0px;" class="gradient">

From the SOurce Code
tdTree1 ---->ctl00_tdTree1
divTree1----> ctl00_divTree1

Can somebody tell me how to set visibility to True & False using Javascript on Master Page Load.