No Clipboard Persistence even with clipboard managers

[Teresa e Junior <teresaejunior@gmail.com>]

I have always used clipboard managers in Linux, but for more than one 
year already I have noticed that clipboard persistence is lost on the 
desktop some hours after booting (the ability to paste after closing the 
source application, see https://wiki.ubuntu.com/ClipboardPersistence). I 
copy the text, close the application, and then I have to choose the item 
in the clipboard manager manually before pasting. Otherwise nothing gets 
pasted.

This is happening on Wheezy 7.8 with Xfce 4.10. I have tried already 
xfce4-clipman, clipit, parcellite, and glipper, and the result is the 
same for them all.

Thanks for your attention!
Teresa e Junior