No types were found in the selection
Class Designer can generate this message for Visual C#, Visual Basic, or Visual C++ code.
To correct this error
For Visual C++ projects, it might take 30 to 60 seconds for a change in the source file to appear in the class diagram. During this delay, Class Designer might generate this error. If this happens, cancel the error and wait for the code element to appear in Class View; after that, Class Designer should be able to display the type.
Check the code in the source file to ensure that it defines a correct type element for the programming language you are using.
Check for spelling errors or incorrect syntax.
If you modify your project structure or move source files in your project, Class Designer can lose track of the type. (This is especially true of the source type of a typedef, base classes, or association types.) If this is the case, drag the modified or relocated source code to the class diagram again to redisplay it.