Can't run in Asp.net

Dear sir:

I try to add report.net in Asp.net, but i can't run it.

in aspx i add code
[ <rsweb:ReportViewer ID="ReportViewer1" runat="server"> </rsweb:ReportViewer>]
and run my web project,
the web can be used ,but when i browse the report web,
it shows error:
[報表檢視器 Web 控制項需要 Web Form 上的 System.Web.UI.ScriptManager]

and detail as follow:
[ScriptManagerNotFoundException: 報表檢視器 Web 控制項需要 Web Form 上的 System.Web.UI.ScriptManager。]
Microsoft.Reporting.WebForms.ReportViewer.CreateChildControls() +210
System.Web.UI.Control.EnsureChildControls() +83
System.Web.UI.Control.PreRenderRecursiveInternal() +42
System.Web.UI.Control.PreRenderRecursiveInternal() +155
System.Web.UI.Control.PreRenderRecursiveInternal() +155
System.Web.UI.Control.PreRenderRecursiveInternal() +155
System.Web.UI.Control.PreRenderRecursiveInternal() +155
System.Web.UI.Control.PreRenderRecursiveInternal() +155
System.Web.UI.Control.PreRenderRecursiveInternal() +155
System.Web.UI.Page.ProcessRequestMain(Boolean includeStagesBeforeAsyncPoint, Boolean includeStagesAfterAsyncPoint) +6660
System.Web.UI.Page.ProcessRequest(Boolean includeStagesBeforeAsyncPoint, Boolean includeStagesAfterAsyncPoint) +245
System.Web.UI.Page.ProcessRequest() +72
System.Web.UI.Page.ProcessRequestWithNoAssert(HttpContext context) +21
System.Web.UI.Page.ProcessRequest(HttpContext context) +58
ASP.twstockweb_dscreport_aspx.ProcessRequest(HttpContext context) in c:\Users\j\AppData\Local\Temp\Temporary ASP.NET Files\vs\2705e872\5524dfe5\App_Web_dt5krjrf.2.cs:0
System.Web.CallHandlerExecutionStep.System.Web.HttpApplication.IExecutionStep.Execute() +341
System.Web.HttpApplication.ExecuteStep(IExecutionStep step, Boolean& completedSynchronously) +69