I know what the problem is. If you installed a new version of JMP (example JMP 14) then next uninstalled an old version of JMP (example JMP 13) the Windows registry key for JMP automation gets deleted. To reset the registry key in JMP go to:
File, Preferences, Windows Specific, the click the button that says Reset Associations.
Go back to Visual Studio and rebuild your solutions, and you are now in business!