Opening Keynote 13 files in older versions of Keynote

I'm having trouble sharing files created in the newest version of keynote (5.1?) with other versions (4.4?). I've tried exporting the file to Keynote 09 through "Export..." but my coworkers are unable to open the file.

I apologize if this has been asked already but how do I either save a version that others can open or revert back to the old keynote?