According to the provided screenshot it seems that the references added to your project are not correct considering the Telerik version in GAC. I would like to ask you to carefully check the references to all Telerik controls in your project and make sure that they are the same version considering the suffix as well (.40). Better yet, you can remove all references and add them anew by using the DLLs from your installation. Make sure that the Target Framework is 4.0 or higher. Delete the license.licx file. After that, you should rebuild your project, close Visual Studio and open it again to make sure that no references are kept in the memory by Visual Studio.
However, if you are still experiencing any further difficulties, feel free to submit a support ticket from your account and provide a sample project demonstrating the undesired behavior. Thus, we would be able to make an adequate analysis of the precise case and assist you further. Thank you in advance.
I hope this information helps.
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