[TYPO3-english] Problems with date : U -> strftime

[Bert Hiddink [BENDOO e-work solutions]]

Hello,

I have this snippet:

temp.copyright = TEXT
temp.copyright.data = date:U
temp.copyright.strftime  = %A, %e. %B %Y

This gives me:
donderdag, 1. januari 1970

...while it should give:
donderdag, 7. mei 2013

What is wrong here? TYPO3 4.7 installation is running on Debian LAMP php5.3.

Any ideas?

Thanks!
Bert