I might help u!!!
TargetControlID="txtDOB"
<asp:TextBox ID="txtDOB" runat="server"></asp:TextBox>
<cc1:CalendarExtender ID="txtDOB_CalendarExtender" runat="server"
Enabled="True" Format="dd/MM/yyyy" TargetControlID="txtDOB">
</cc1:CalendarExtender>
Thanx
~~Karthik.J~~