IIS Express And Internal Server Error with reportviewer 10.0

Hi:

I meet a problem when using IIS Express. I using reportviewer 10.0 in my project, 

however, when performing debug, it will show error page and its topic is 

Internal Server Error, and it implies the add name of "ReportViewerWebControlHandler" 

is duplicated. However, if I take off the sentence as following:

<handlers><remove name="WebServiceHandlerFactory-Integrated" /><!--<add name="ReportViewerWebControlHandler" preCondition="integratedMode" verb="*" path="Reserved.ReportViewerWebControl.axd" type="Microsoft.Reporting.WebForms.HttpHandler, Microsoft.ReportViewer.WebForms, Version=10.0.0.0, Culture=neutral, PublicKeyToken=b03f5f7f11d50a3a" />--></handlers>

the error will pass, but when performing reportviewer, it will show config error, it need the upper setting.

It is very confused, and I don't know how to fix that. 

Is there any way to handle that, any suggestion is highly appreciated. Thanks.