ASP.NET - asp.net menu control

hi friends

when i click on menu item it disappear from the screen 
what properties to be added

my code is

<asp:Menu ID="Menu_MainMenu" runat="server" BackColor="#B5C7DE" 
            DynamicHorizontalOffset="2" Font-Names="Verdana" Font-Size="0.8em"  
            ForeColor="#284E98" Orientation="Horizontal" 
            StaticSubMenuIndent="1px" MaximumDynamicDisplayLevels="1">
             <StaticMenuItemStyle BackColor="Red" />
            
            <StaticHoverStyle BackColor="Blue" ForeColor="#990099"  />
             <StaticMenuStyle BackColor="#3399FF" />
            <StaticSelectedStyle BackColor="Red " ForeColor="#990000" />
            <DynamicHoverStyle BackColor="#0000CC" ForeColor="White" />
            <DynamicMenuStyle BackColor="#E81767" />
            <StaticSelectedStyle BackColor="#507CD1" />
            <DynamicSelectedStyle BackColor="#507CD1" />
            <DynamicMenuItemStyle HorizontalPadding="1px" VerticalPadding="2px" 
                 BackColor="#000099" ForeColor="White"/>
           
            <Items>
                <asp:MenuItem Text="About Us" Value="About Us">
                    <asp:MenuItem Text="Our Team" Value="Our"></asp:MenuItem>
                    <asp:MenuItem Text="CEO Speaks" Value="CEO Speaks"></asp:MenuItem>
                    <asp:MenuItem Text="Our Philosophy" Value="Our Philosophy"></asp:MenuItem>
                </asp:MenuItem>
                <asp:MenuItem Text="Services" Value="New Item">
                    <asp:MenuItem Text="Free Quotes" Value="Free Quotes"></asp:MenuItem>
                    <asp:MenuItem Text="Coverage Calculator" Value="Coverage Calculator">
                    </asp:MenuItem>
                    <asp:MenuItem Text="Easy Buying" Value="Easy Buying"></asp:MenuItem>
                    <asp:MenuItem Text="24 hrs Interactive Support" 
                        Value="24 hrs Interactive Support"></asp:MenuItem>
                    <asp:MenuItem Text="Reminder Service" Value="Reminder Service"></asp:MenuItem>
                </asp:MenuItem>
                <asp:MenuItem Text="Special Products" Value="Special Products">
                    <asp:MenuItem Text="Senior Citizen Cover" Value="Senior Citizen Cover">
                    </asp:MenuItem>
                    <asp:MenuItem Text="Diabetic Cover" Value="Diabetic Cover"></asp:MenuItem>
                    <asp:MenuItem Text="Corporate Pack" Value="Corporate Pack"></asp:MenuItem>
                    <asp:MenuItem Text="Family Pack" Value="Family Pack"></asp:MenuItem>
                    <asp:MenuItem Text="Materinity Pack" Value="Materinity Pack"></asp:MenuItem>
                    <asp:MenuItem Text="Top_Up Cover" Value="Top_Up Cover"></asp:MenuItem>
                    <asp:MenuItem Text="Overseas Cover" Value="Overseas Cover"></asp:MenuItem>
                </asp:MenuItem>
                <asp:MenuItem Text="Claims" Value="Claims">
                    <asp:MenuItem Text="Claim Settlement" Value="Claim Settlement"></asp:MenuItem>
                    <asp:MenuItem Text="Guidelines for Health Claims" 
                        Value="Guidelines for Health Claims"></asp:MenuItem>
                    <asp:MenuItem Text="Do's &amp;Don'ts" Value="Do's &amp;Don'ts"></asp:MenuItem>
                    <asp:MenuItem Text="Contact Us" Value="Contact Us"></asp:MenuItem>
                </asp:MenuItem>
                <asp:MenuItem Text="Buying Guide" Value="Buying Guide">
                    <asp:MenuItem Text="3 Point Mini Guide" Value="3 Point Mini Guide">
                    </asp:MenuItem>
                    <asp:MenuItem Text="Pre-purchase" Value="Pre-purchase"></asp:MenuItem>
                    <asp:MenuItem Text="Policy Checklist" Value="Policy Checklist"></asp:MenuItem>
                    <asp:MenuItem Text="Post-purchase" Value="Post-purchase"></asp:MenuItem>
                    <asp:MenuItem Text="The Fine Print" Value="The Fine Print"></asp:MenuItem>
                </asp:MenuItem>
               
                <asp:MenuItem Text="Customer Care" Value="Customer Care">
                    <asp:MenuItem Text="Register with Us" Value="Register with Us"></asp:MenuItem>
                    <asp:MenuItem Text="Renew My Policy" Value="Renew My Policy"></asp:MenuItem>
                    <asp:MenuItem Text="Post Your Query" Value="Post Your Query"></asp:MenuItem>
                    <asp:MenuItem Text="Missed call service" Value="Missed call service">
                    </asp:MenuItem>
                    <asp:MenuItem Text="Contact us" Value="Contact us"></asp:MenuItem>
                </asp:MenuItem>
            </Items>
        </asp:Menu>

As an option you can use ajax hover menu

<asp:ScriptManager ID="ScriptManager1" runat="server">
</asp:ScriptManager>
<cc1:HoverMenuExtender ID="HoverMenuExtender2" runat="Server" PopupControlID="sub"
PopupPosition="bottom" TargetControlID="lnkSub" PopDelay="25" Enabled="true" />



 
<table bordercolor="black" cellpadding="0" cellspacing="0" id="t" border="0" runat="server"
bgcolor="#4A669C">
<tr><td height="20px" backcolor="blue" style="width: 44px">
<asp:LinkButton ID="lnkHome" Text="Home" ForeColor="White" runat="server" PostBackUrl="Default.aspx" />
</td>
<td height="20px" width="100">
<asp:LinkButton ID="lnkSub" ForeColor="White" runat="server" PostBackUrl="#" Text="Subject"/>
</td></tr>
</table>
 
<table runat="server" id="sub" bgcolor="#E2E9F1" width="100">
<tr><td><a href="#">ASP.NET</a><br /><a href="#"> C#</a>
<br /><a href="#">VB.NET</a><br /><a href="#">J#</a><br />
</td></tr>
</table>

There is no problem with the menu control, Can you tell me to which page it is being rediret when you click on the menu item.
Can you also check whether the menu is present in the target page which is redirected?

Are you placed the Menu Control on Master page / User control which is common to the application?