[Zope] timezone question: is someone using CEST ??

Hello, I live in the CEST timezone (gmt+1) I have problem with the calendar tag: it says : Error:DateTimeError Error Message:Unrecognized timezone inside DateTime.py they are references to a lot of zone (after class_cache:) but no mention of 'CEST'. a DTML like: time:<!--#var ZopeTime fmt="timezone"-->.<br> produce no information, The normat var ZopeTime works well.I have RH 5.1 ,zope 1.10.2, python 1.5.1 Is it normal? Is the CEST reference missing inside DateTime.py? Or shall I move to another country?? Gilles Lavaux