I am not sure that I understand what you mean by saying that the assembly is not supported. Can you clarify this, please?
In the meantime, you can try to delete manually the "bin" and "obj" folders from you projects and then Clean and Rebuild your solution. You can also check if all other Telerik assemblies are the same version like the DataVisualization and if your project's Target Framework is set to .NET 4.5
If this doesn't help can you please open a new Support Ticket and provide us a project demonstrating the reported behavior? This will allow us to test it locally and investigate further the reason behind the issue.
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