Index: tol/OIS/oisloader.cpp
===================================================================
--- tol/OIS/oisloader.cpp	(revision d7349ff3605247c2ec22e0b27c391151640e31cd)
+++ tol/OIS/oisloader.cpp	(revision a72f6422b69ea05ee32ea8cd8a2d107ad1f7ae5d)
@@ -1407,11 +1407,12 @@
           { result = x; }
           BUserTimeSerie* ser = (BUserTimeSerie*)result;
-          if(dating!=ser->Dating())
-          {
-            if(forceStoredTimeSet_!=0)
+          BTimeSet* serDating = ser->Dating();  
+          if(dating!=serDating)
+          {
+            if(!serDating || (forceStoredTimeSet_!=0))
             {
               ser->PutDating(dating);
             }
-            if(!dating->IsCompatibleWith(*(ser->Dating()),beginCache,endCache))
+            if(serDating && !dating->IsCompatibleWith(*serDating,beginCache,endCache))
             {
               Warning(BText("Dating of loaded Serie ")+name+"="+expr+