I had issues with pyperclip. Copying text to the clipboard did not work. Found the solution for my problem on the pypi page of pyperclip:

"... On Linux, this module makes use of the xclip or xsel commands, which should come with the os. Otherwise run “sudo apt-get install xclip” or “sudo apt-get install xsel” (Note: xsel does not always seem to work.)

Otherwise on Linux, you will need the gtk or PyQt4 modules installed."

Everything works fine now, after I have installed xclip.