[Zope] can not use umlaute with structered text

Hi there, I found out that as soon a text contains umlauts the codes to change its formatting like **xxx** do not work anymore. I was digging in the source and found locale.setlocale. However this function does not work. Calling it creates a traceback saying that the local can not be changed. How can this function be used. Or is there an other way to be able to use umlauts? thanks Robert