Opening files from the Finder, including files authored by Adobe applications, does not open them in the original authoring application.
Note: Mac OS X 10.6 eliminates the use of creator codes in its Launch Services methods for determining the preferred application with which to open a file. Files are opened based on explicit application associations for a specific file, all files of that type, or based on the file extension. Omitting a file extension from the filename increases the likelihood of a file not opening properly.
If a file does not open, use one of more of the following solutions:
Use filename extensions.
Associate all files of a given type with your preferred application:
Use custom filename extensions to differentiate files of the same type from different creators. For example, use the extension .jpg to associate files with your preferred web browser, and use the extension .jpeg to associate all JPEG files with Adobe Photoshop.