Visual Studio do not add my component (from a DLL) to the toolbox even if I reference it

I had this problem with @AndrewFinnell's solution:

There are no components in 'c:....\XXXX.dll' that can be placed on the toolbox.

So I solved with drag and drop:

• open Windows explorer and navigate to the DLL
• drag the DLL and drop it on Visual Studio in the Toolbox, exactly where you want your components to appear.

I also realized that some components may have compatibility issues with certain .NET Framework versions. For instance A Professional Calendar/Agenda View That You Will Use seems not to work with .NET 4.5, while it does with .NET 4.

• Right-click in the toolbox.
• Click "Choose Items..."
• Click "Browse..."
• Navigate to your DLL and click Open
• Then click "Ok"

Your components should then show up

The way I found to make this working is:

1. Add the dll, reference it
2. Compile the project
3. Save the solution and restart visual studio

And then controls show up in toolbox (not always working, I think is a sort of visual studio bug)