I can hibernate correctly my laptop, by the command sudo pm-hibernate. Even the resume works well! But if I try to hibernate by the power menu (Unity on Ubuntu 14.04 with hibernate option enabled), nothing happens. It seems that the hibernate option on power menu doesn't execute the command "sudo pm-hibernate" and when I click on this option, the screen become black for two seconds and after it returns the same as before...
How can I do? Thanks