--- tz.py	2004-12-13 19:46:32.143192000 -0600
+++ tzOld.py	2004-12-13 19:46:24.892766400 -0600
@@ -758,10 +758,10 @@
                         if not founddtstart:
                             raise ValueError, \
                                   "mandatory DTSTART not found"
-                        if tzoffsetfrom is None:
+                        if not tzoffsetfrom:
                             raise ValueError, \
                                   "mandatory TZOFFSETFROM not found"
-                        if tzoffsetto is None:
+                        if not tzoffsetto:
                             raise ValueError, \
                                   "mandatory TZOFFSETFROM not found"
                         # Process component