Report Viewer not working on .Net Framework 4.0

Report Viewer does not work on a .NET Framework 4.0

Once I provide Report Server and path details and run the application it fails with the error

The Report Viewer Web Control HTTP Handler has not been registered in the application's web.config file.
Add <add verb="*" path="Reserved.ReportViewerWebControl.axd" type = "Microsoft.Reporting.WebForms.HttpHandler, Microsoft.ReportViewer.WebForms, Version=11.0.0.0, Culture=neutral, PublicKeyToken=89845dcd8080cc91" /> to the system.web/httpHandlers section of the web.config file, or add <add name="ReportViewerWebControlHandler" preCondition="integratedMode" verb="*" path="Reserved.ReportViewerWebControl.axd" type="Microsoft.Reporting.WebForms.HttpHandler, Microsoft.ReportViewer.WebForms, Version=11.0.0.0, Culture=neutral, PublicKeyToken=89845dcd8080cc91" /> to the system.webServer/handlers section for Internet Information Services 7 or later.

I have the same http handler information on the web.config and I have referenced the version 11 report viewer DLL to my application.

I tried to replicate this scenario on .NET Framework 4.5 and 3.5. There it worked perfectly alright.

Does anyone has a clue of what might be wrong ?