timestamp doesn’t work in 2.2

hi,
i’ve downloaded the 2.2 version (tar.gz format) and when i set timestamp to articles it doesn’t work.
The articles appear on my dashboard with the time remaining to the publishing on the right, but when it is reached it is not published. Instead the time starts to grow up, minute after minute.

I used the same method that i used in wp 1.5 to publish articles and it worked.

Can someone help me? (i’ve already checked the time on my server)