The file, encrypted using PGPBlackbox, is displayed by PGP in "Secure Viewer" window and it's not possible to save the file (one gets the error "This message is for your eyes only"). Why?
Remember to set ElPGPWriter.Filename to the name of the original file when encrypting the data. If you are not encrypting the file (but generic data), you can use almost any name. Just ensure that it fits the general rules for file names (only allowed characters, limited maximum length).