ajax calendar not popping up on button click

i have done the process completely which i have mentioned below. Inspite of getting no errors and even getting text box and button displayed ,the calendar is not popping up on button click.

actually i am using visual studio 2005 and it obviously has framework 2.0

downloaded and installed ajax extension also.
please see the source code once

body
form id="form1" runat="server"
div
asp:ScriptManager ID="ScriptManager1" runat="server"
/asp:ScriptManager


asp:CalendarExtender ID="CalendarExtender1" TargetControlID="TextBox1" runat="server" Enabled="true"
/asp:CalendarExtender

asp:TextBox ID="TextBox1" runat="server"/asp:TextBox


/div 
/form

/body

and resolve my error