I'm running OSX 10.6.8. Lets say I have two terminal windows open and in each window I begin editing a different file using emacs. In the first file I select some text and then copy it (M-w), and in the second file I then try and paste it (C-y). I thought this would paste what I copied from the other file but instead I get the error message "previous command was not a yank". Those commands work just fine for copying and pasting within a single file, how do I copy and paste between different files?