Hi Barqitta,
Most likely the target framework is not 4.0 - check out the following page:
http://helpdotnetvision.nevron.com/GettingStarted_IntegratingInWindowsForms_Integrating_In_Windows_Forms.html
Shortly the docs say:
VS 2010 users must switch the target framework to ".NET Framework 4" as by default Windows Forms applications target ".NET Framework 4 Client Profile". This is required, because Nevron Chart for WinForms uses design time support features that are not present in ".NET Framework 4 Client Profile". To do this right click on the project in Solution Explorer and select properties. On the Application tab go to "Target Framework" and select ".NET Framework 4".
Hope this helps - let us know if you meet any problems.