asp.net ajax UpdatePanel控件使用
请问一下   我要现有web项目中使用Updatepanel   会提示有错误:Sys未定义     难道用这个控件还要新建一个asp.net   AJAX-Enabled   Web   Site   才行吗?

------解决方案--------------------
正好遇到过这个问题，在webconfig中加入:
<httpHandlers>
<remove verb= "* " path= "*.asmx "/>
<add verb= "* " path= "*.asmx " validate= "false " type= "System.Web.Script.Services.ScriptHandlerFactory, System.Web.Extensions, Version=1.0.61025.0, Culture=neutral, PublicKeyToken=31bf3856ad364e35 "/>
<add verb= "* " path= "*_AppService.axd " validate= "false " type= "System.Web.Script.Services.ScriptHandlerFactory, System.Web.Extensions, Version=1.0.61025.0, Culture=neutral, PublicKeyToken=31bf3856ad364e35 "/>
<add verb= "GET,HEAD " path= "ScriptResource.axd " type= "System.Web.Handlers.ScriptResourceHandler, System.Web.Extensions, Version=1.0.61025.0, Culture=neutral, PublicKeyToken=31bf3856ad364e35 " validate= "false "/>
</httpHandlers>
<compilation debug= "true ">
<assemblies>
<add assembly= "System.Web.Extensions, Version=1.0.61025.0, Culture=neutral, PublicKeyToken=31BF3856AD364E35 "/>
</assemblies>
</compilation>

注意不要把compilation节重复了。