Show Hide HTML Menu item based on Session in ASP.Net

i want to visible true   List menus     on click off ListButton.

that time i m passing session its not working .

just  removing the code of session its working properly.

i am using list menu in the mainmaster.master(MasterPage) 

I want to Hide and Display menus on the Content Page

<div class="menu">
    <table style="width: 100%; text-align: center;">
        <tr>
            <td style="text-align: center" colspan="4">
                <div id="nav">
                    <ul>
                        <li><a href="BillPrepare.aspx<%Session["Menu1"] = 1; %>">Bill Preparation</a></li>
                        <li><a href="Send To Verification.aspx">Send To Verification</a> </li>
                        <li><a href="Bill Pass Details.aspx">Bill Paas Details</a> </li>
                        <li><a href="Print.aspx">Print</a></li>
                        <li><a href="#">Reports</a> </li>
                    </ul>
                </div>
            </td>
        </tr>
    </table>
</div>