diff --git a/SOPE/NGCards/ChangeLog b/SOPE/NGCards/ChangeLog
index e13917d67..3ddc72939 100644
--- a/SOPE/NGCards/ChangeLog
+++ b/SOPE/NGCards/ChangeLog
@@ -1,3 +1,8 @@
+2007-11-29  Wolfgang Sourdeau  <wsourdeau@inverse.ca>
+
+	* iCalDateTime.m ([iCalDateTime -timeZone]): log a message if the
+	corresponding timezone isn't found.
+
 2007-11-26  Wolfgang Sourdeau  <wsourdeau@inverse.ca>
 
 	* iCalCalendar.m ([iCalCalendar -versitString]): same as below,
diff --git a/SOPE/NGCards/iCalDateTime.m b/SOPE/NGCards/iCalDateTime.m
index 127be961a..159545e81 100644
--- a/SOPE/NGCards/iCalDateTime.m
+++ b/SOPE/NGCards/iCalDateTime.m
@@ -23,6 +23,8 @@
 #import <Foundation/NSString.h>
 #import <Foundation/NSTimeZone.h>
 
+#import <NGExtensions/NSObject+Logs.h>
+
 #import "NSCalendarDate+NGCards.h"
 #import "NSString+NGCards.h"
 
@@ -76,13 +78,17 @@
   NSString *tzId;
   iCalTimeZone *timeZone;
 
+  timeZone = nil;
+
   tzId = [self value: 0 ofAttribute: @"tzid"];
-  calendar
-    = (iCalCalendar *) [self searchParentOfClass: [iCalCalendar class]];
-  if ([tzId length] && calendar)
-    timeZone = [calendar timeZoneWithId: tzId];
-  else
-    timeZone = nil;
+  if ([tzId length])
+    {
+      calendar
+	= (iCalCalendar *) [self searchParentOfClass: [iCalCalendar class]];
+      timeZone = [calendar timeZoneWithId: tzId];
+      if (!timeZone)
+	[self logWithFormat: @"timezone '%@' not found in calendar", tzId];
+    }
 
   return timeZone;
 }