asp.net gridview simple question hope someone can answer ^_^ part 2

See more:

ASP.NET

Gridview

Hello again guys. Got a few question here (Again). Alright I think I could do it on hyperlink but my task is to use imagebutton and redirect it to another with query string such as this one http://localhost:1884/TrainingPlan/Admin/UserUpdate.aspx?Username='blahblah'. Now im getting an error here. Could someone help me (Again ^_^)

<asp:GridView ID="gvUserList" runat="server" AutoGenerateColumns="false">
    <Columns>
    <asp:BoundField HeaderText="Username" DataField="Username"  />

    <asp:TemplateField HeaderText="Name">
    <ItemTemplate>
        <asp:Label ID="lblfirstname" runat="server" Text='<%# Eval("Firstname")%>'> </asp:Label>&nbsp;
        <asp:Label ID="lbllastname" runat="server" Text='<%# Eval("Lastname")%>'> </asp:Label>
    </ItemTemplate>
    </asp:TemplateField>

    <asp:TemplateField >
         <ItemTemplate>
             <asp:ImageButton ID="Imagebtnedit" runat="server" OnClientClick="window.location.href= <%#" UserUpdate.aspx?Username=" & Eval("Username")%>'"  />
        </ItemTemplate>
    </asp:TemplateField>


    </Columns>
    </asp:GridView>
    <br />
    <br />

Thanks and more power