This is your web.config issue:
Try Adding the following in the system.web tag
<httphandlers>
<remove verb="*" path="*.asmx" />
<add verb="*" path="*.asmx" validate="false" type="System.Web.Script.Services.ScriptHandlerFactory, System.Web.Extensions, Version=3.5.0.0, Culture=neutral, PublicKeyToken=31bf3856ad364e35" />
<add verb="GET" path="ScriptResource.axd" type="System.Web.Handlers.ScriptResourceHandler" validate="false" />
</httphandlers>
OR follow the link:
sys-is-undefined
Hope it helps :)