Exception on script manager

hi,

I am getting exception on scriptmanager like

   Exception type: InvalidOperationException
                       Exception message: The page is performing an async pos
                   tback but the ScriptManager.SupportsPartialRendering prope
                   rty is set to false. Ensure that the property is set to tr
                   ue during an async postback.
                      at System.Web.UI.ScriptManager.OnPageInitComplete(Objec
                   t sender, EventArgs e)

so anybody please tell me how to fix this issue.thanks