RadScriptManager not working

[Joseph]

I get this error every time I try to load a page

'~/Telerik.Web.UI.WebResource.axd' is missing in web.config. RadScriptManager requires a HttpHandler registration in web.config. Please, use the control Smart Tag to add the handler automatically, or see the help for more information: Controls > RadScriptManager

I am confused where to go from here I tried adding it manually in the web.config file. Didn't work. I don't see smart tag. I am just very confused by this,

[Shinu]

Hello Joseph,

Telerik uses a custom AXD to stream down resources.  If you are using the RadScriptManager, open up the designer, click the smart tag button, and there is an option to automatically add this definition to the web.config file.
Check the following help documentation as well.
RadScriptManager

Thanks,
Shinu.