[Zope] Trouble with dates in an External Method

I'm having trouble using dates in an external method. I can't get it to import the python DateTime module. I need to compare two dates which are in string form in the external method. I know that this isn't a good description of what I'm trying to do but I'm new to Zope development. If this should go to a different mailing list please let me know. Thanks in advance for any help, Steven