incopy can't save the corrected files

hi,I have a problem,which make the editors crazy. One editor change the file through the Incopy in his computer,another editor change the file again in her computer,and the third one correct the same file in his computer.They all save the correted files.but indesign can't see the files which was correctted by the three editors.At the last all corrected work lost.

I don't understand why the works can't save through the Incopy.