Using Platform-independent File Names in Programs
Make sure that the customizing tables contain definitions for the logical file name you want to use, and that these definitions produce the intended file name conversion. Use transaction FILE to inspect existing definitions or to specify new ones. (For details refer to the implementation guide in section Basis Components ® System Administration ® Platform-independent File Names.)
Make sure the physical paths referred to in these definitions do actually exist in the file system at runtime. If necessary, create the respective directories or consult your system administrator.
Test the file name conversion by calling the function module FILE_GET_NAME, using transaction SE37.
Include a call of the function module in your program. (In the ABAP/4 editor you can do this with function Edit ® Insert statement...)
For more information on storing files on the application server and on the presentation server please refer to Working with Files in the ABAP/4 User's Guide.
Problems with storing files may sometimes be due to a mismatch between the paths defined for platform-independent file names and the file system. Generation of a valid platform-specific file name by the function module FILE_GET_NAME is not sufficient; the path generated must also exist in the file system at runtime.