How to attach CompareValidator to DateTime control

<sharePoint:DateTimeControl ID="dteDemo" runat="server" DateOnly="true" /> 
<asp:CompareValidator id="valDate" runat="server"
        ControlToValidate="dteDemo$dteDemoDate"
         Type="Date"
 Operator="DataTypeCheck"

 ErrorMessage="Please enter an valid date"> 

</asp:CompareValidator >