On occasion, when you build a merged application with 4D and 4D Engine in OSX, you may find that this application gives an error when being launched from OS9. The problem is that once the application is created, do not directly move the app to your OS9 partition from the OSX environment. Instead, use the latest version of Stuffit file compression tool to stuff your application. Transfering files this way will avoid any corruption that may occur while transferring your application between OSX and OS9.