Design view problem of user control menu

I have got a user control with this code but i couldnt see
anything in the design view of ascx page
What couls be the problem?

<%@ Control language="C#" AutoEventWireup="false"
Codebehind="m_ts_coursesched_popup.ascx.cs"
TargetSchema="http://schemas.microsoft.com/intellisense/ie5
"%>

<%@ Register TagPrefix="iewc"
Namespace="Microsoft.Web.UI.WebControls"
Assembly="Microsoft.Web.UI.WebControls, Version=1.0.2.226,
Culture=neutral, PublicKeyToken=31bf3856ad364e35" %>

<asp:Panel id="Panel1" runat="server" Height="600px"
Width="200px">

<iewc:Toolbar id="m_ts_coursesched_popup" style="Z-INDEX:
101; LEFT: 5px; OVERFLOW: auto; POSITION: absolute; TOP:
63px" runat="server" Height="490px" Width="196px"
Color="Blue" Orientation="Vertical" >

<iewc:ToolbarLabel Text="Popup" ID="
m_popup"></iewc:ToolbarLabel>

<iewc:ToolbarButton Text="Schedule" ID=" m_schedule"
DefaultStyle="border-right:#AD1021 2px Solid;border-
top:#AD1021 2px Solid;font-size:12px;border-left:#AD1021
2px Solid;border-bottom:#AD1021 2px Solid;font-
family:Tahoma;color:Teal;" HoverStyle="border-
right:#Yellow 2px solid;border-top:#Yellow 2px solid;font-
size:12px;border-left:#Yellow 2px solid;border-
bottom:#Yellow 2px solid;font-
family:Arial;color:Teal;background-
color:Yellow;"></iewc:ToolbarButton>

</iewc:Toolbar>
</asp:Panel>



Thank you