calling [Ajax.AjaxMethod()] not working

hi all,

i have converted a web application from asp.net 2.0 to asp.net4.0. Originally the code behind  [Ajax.AjaxMethod()] methods referring Ajax.dll(which is under bin folder, Run Time Version v1.1.4322).

assume that i have a method in code behind like below

[Ajax.AjaxMethod()]
        public DataView GetDet()
        {
        }

and calling above function from javascript like this

POI.GetDet(ExpandMnetLine_Response);

it was working fine in my old server.

Now, i pulished the same code into 64 bit Windows 2008 R2 Server there, wherever the AJAX methods are calling those places, it raising javascrip error as "object not defined" etc.,

may i know what is this problem and how to resolve this issue?