What's wrong with this SQLDataSource Control?

I must be a plank, but I keep getting "expected )", "invalid expression term :", "expeced ," etc for line 8 (the sqldatasource line)

Code:

---

<%@ Page Language="c#" MasterPageFile="~/MasterPage.master" CodeFile="~/Default2.aspx.cs" Inherits="Default2" %>

<asp:Content ID="Content1" ContentPlaceHolderID="ContentPlaceHolder1" runat="server">

<asp:GridView ID="GridView1" DataSourceID="SQLDataSource1" AutoGenerateColumns="False" runat="server">

</asp:GridView>
<asp:SqlDataSource ID="SQLDataSource1" ConnectionString="<%# ConnectionStrings:WroxUnited %>" runat="server"
SelectCommand="SELECT * FROM [Fixtures]"></asp:SqlDataSource>

</asp:Content>

---

Post the exact text of the error you get.

ConnectionString="<%$ ConnectionStrings: WroxUnited %>"