I have a DatePicker custom control that I am trying to add to toolbox. The name of the file is BasicFrame.WebControls.BasicDatePicker.dll and I go through the procedure of right click in Toolbox > Choose Items and then selecting the file after browsing to it under .NET Framework components.
I however get this error message:
There are no components in that can be placed on toolbox
Why do I get this message and how can I resolve it?
Have you checked the visibility of the custom classes?
If you haven't declared them as public they will default to internal and hence aren't exposed to Visual Studio for use.
In some cases you can solve this problem 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
Sometimes drag and drop does not work also. In this case you can
- open Windows explorer and navigate to the DLL
- copy the dll file and paste it directly on the toolbox tab you wish to place the controls.
来源：https://stackoverflow.com/questions/14199202/there-are-no-components-in-dll-that-can-be-placed-on-toolbox