RADGrid Error using latest version

[Simon]

I have read the forums and removed all assemblies , cleared cache and all other thins but I am getting this error still:

RadGrid - RadGrid1System.InvalidCastException: [A]Telerik.Web.UI.RadGrid cannot be cast to
[B]Telerik.Web.UI.RadGrid. Type A originates from 'Telerik.Web.UI, Version=2013.1.403.40,
Culture=neutral, PublicKeyToken=121fae78165ba3d4' in the context 'LoadNeither' at location
'C:\Users\simon.SOUTHGATE\AppData\Local\Microsoft\VisualStudio\11.0\ProjectAssemblies\mxvuxvpg01\Telerik.Web.UI.dll'.
Type B originates from 'Telerik.Web.UI, Version=2013.1.403.40, Culture=neutral, PublicKeyToken=121fae78165ba3d4'
in the context 'LoadNeither' at location 'C:\Users\simon.SOUTHGATE\AppData\Local\Microsoft\VisualStudio\11.0\ProjectAssemblies\b1apdsv701\telerik.web.ui.dll'.
at Telerik.Web.Design.RadGridDesigner.GetDesignTimeHtml(DesignerRegionCollection regions) at System.Web.UI.Design.ControlDesigner.GetViewRendering(ControlDesigner designer)

Can anyone help please!!!!

[Eyup]

Hi Simon,

The reasons for the issue you are currently observing are explained  in the last section of the following topic:
Design-time Troubleshooting

I hope the suggested solution will be helpful. If the problem remains, it may be because the copied files in the new project have a reference to the old version of the controls. Please check your mark-up assembly references, as well as these in the web config. If the problem remains, modify your GAC references as explained in the provided links.

In addition, you can check out some other topics in case similar issues arise:
  http://www.telerik.com/help/aspnet-ajax/introduction-troubleshooting-skins.html
 http://www.telerik.com/help/aspnet-ajax/introduction-troubleshooting.html
 RadControls Trial Message

Could you please share whether you have tried the Telerik Upgrade Wizard?
http://www.telerik.com/help/aspnet-ajax/introduction-vsx-upgrade-wizard.html

Regards,
Eyup
the Telerik team