'NSFetchedResultsController does not support both change tracking and fetch request's with NSDictionaryResultType'

Question

I have an application that was running just fine under OS3+. But it does not work under OS4. I get the following error message : 'NSFetchedResultsController does not support both change tracking and fetch request's with NSDictionaryResultType'

Does it ring a bell to anyone here?

• (NSFetchedResultsController *)fetchedResultsController {

  if (fetchedResultsController != nil) { return fetchedResultsController; }

  /* Set up the fetched results controller. */ // Create the fetch request for the entity. NSFetchRequest *fetchRequest = [[NSFetchRequest alloc] init]; // Edit the entity name as appropriate. NSEntityDescription *entity = [NSEntityDescription entityForName:@"myEntity" inManagedObjectContext:managedObjectContext];

  [fetchRequest setEntity:myEntity];

  [fetchRequest setResultType:NSDictionaryResultType];

  [fetchRequest setPropertiesToFetch :[NSArray arrayWithObjects:@"FIELD1",@"FIELD2",@"FIELD3",@"FIELD4",@"FIELD5",nil]];

  // Setting unique values

  [fetchRequest setReturnsDistinctResults:YES];

  // Edit the sort key as appropriate. NSSortDescriptor *initialDescriptor = [[NSSortDescriptor alloc] initWithKey:@"FIELD1" ascending:YES];

  NSArray *sortDescriptors = [[NSArray alloc] initWithObjects:initialDescriptor, nil];

  [fetchRequest setSortDescriptors:sortDescriptors];

  // Edit the section name key path and cache name if appropriate. // nil for section name key path means "no sections".

  NSFetchedResultsController *aFetchedResultsController = [[NSFetchedResultsController alloc] initWithFetchRequest:fetchRequest managedObjectContext:managedObjectContext sectionNameKeyPath:@"FIELD1" cacheName:@"myCache"];

  aFetchedResultsController.delegate = self; self.fetchedResultsController = aFetchedResultsController; [aFetchedResultsController release]; [fetchRequest release]; [initialDescriptor release]; [sortDescriptors release];

  return fetchedResultsController; }

Thanks in advance.