asp.net - vb.net page doesnt recognize scriptmanager tag

I am trying to use the script manager tag to relay data from a javascript function to code behind and its not working I get this error:

Server Error in '/' Application.
--------------------------------------------------------------------------------

Parser Error 
Description: An error occurred during the parsing of a resource required to service this request. Please review the following specific parse error details and modify your source file appropriately. 

Parser Error Message: Unknown server tag 'asp:scriptmanager'.

Source Error: 


Line 228:    </script>  
Line 229:    
Line 230:    <asp:scriptmanager ID="Scriptmanager1" runat="server" EnablePageMethods="true"></asp:scriptmanager>
Line 231:    <asp:HiddenField runat="server" ID="sessionDuration" />
Line 232:        
 

Source File: /Shoe_Comp/ShoeMobile.aspx    Line: 230 


--------------------------------------------------------------------------------
Version Information: Microsoft .NET Framework Version:2.0.50727.5448; ASP.NET Version:2.0.50727.5420

Select allOpen in new window