Strange Error

I have a datasource which I use with a gridview, here is the line

<asp:SqlDataSource ID="sub_table_conn" runat="server" ConnectionString="<%$ ConnectionSrings:textConn %>" SelectCommand="SELECT sub_type_id,sub_type FROM tblsubcategories">
        </asp:SqlDataSource>

No I get this message.  Do I have to register the connection or something,? Thanks in advance Andrew

Here is the error

Parser Error Message: The expression prefix 'ConnectionSrings' was not recognized.  Please correct the prefix or register the prefix in the <expressionBuilders> section of configuration.

Source Error:


Line 12:         <asp:GridView ID="GridView1" runat="server" DataSourceID="sub_table_conn">
Line 13:         </asp:GridView>
Line 14:         <asp:SqlDataSource ID="sub_table_conn" runat="server" SelectCommand="SELECT sub_type_id,sub_type FROM tblsubcategories" ConnectionString="<%$ ConnectionSrings: textConn %>" >
Line 15:         </asp:SqlDataSource>
Line 16:     </div>
 

Source File: /andy/test_area/default.aspx    Line: 14