Need Help Setting Default DateTime On SqlDataSource Control

I thought this would be easy.  I have a repeater control and a sqldatasource control.  I am trying to filter the select statement using DateTime.Now.ToString() and keep getting an invalid date string format.  The control is on a content page in my asp.net site.  On the master page this <%= DateTime.Now.ToLongDateString() %>  works to display the current date.  If I try and put <%= DateTime.Now.ToString() %> in the Default value of the SelectParameter it does not work.  No intellisense either so I am assuming I am missing something.  Here is the code... pretty basic really.

<asp:Repeater ID="Repeater1" runat="server" DataSourceID="sqlDSnews">

<ItemTemplate>

<h3><%# Eval("newTitle")%></h3>

</ItemTemplate>

</asp:Repeater>

<asp:SqlDataSource

ID="sqlDSnews"

runat="server"

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

SelectCommand="SELECT [newTitle], [newsDetails], [dateExpires], [newsImage], [dateCreated] FROM [News] WHERE (([GroupID] = @GroupID) AND ([dateExpires] >= @dateExpires))">

<SelectParameters>

<asp:QueryStringParameter DefaultValue="0" Name="GroupID" QueryStringField="Gid" Type="Int32" />

<asp:Parameter Name="dateExpires" DefaultValue='<%= DateTime.Now.ToString() %> 'Type="DateTime" />

</SelectParameters>

</asp:SqlDataSource>

** NOTE the DateTime does not show up in blue - if that helps with a solution **