What would prevent an editable NSTableColumn from being editable on double-click?

I have an NSTableView with a single column. This column has "Editable" checked in Interface Builder, but double-clicking on a cell in the table view does nothing. I've confirmed (in -tableView:viewForTableColumn:row: by checking [tableColumn isEditable]) that the table column has the editable flag set. What would prevent the column from being editing if isEditable == YES?

It's been suggested that I include my datasource and delegate code. The dataArray is a property that stores NSManagedObject subclass objects. listPopupButton selects which entity to be viewing in an NSTableView that can display different entities, all of which have only a name attribute (as indicated by the nameOnlyItems method that returns an array of these).

- (NSInteger)numberOfRowsInTableView:(NSTableView *)tableView {
  return [[self dataArray] count];
}

- (NSView *)tableView:(NSTableView *)tableView
   viewForTableColumn:(NSTableColumn *)tableColumn
                  row:(NSInteger)row {
  NSTableCellView *cellView;
  NSNumber *index = [NSNumber numberWithInteger:[[self listPopupButton] indexOfSelectedItem]];

  if ([[self nameOnlyItems] containsObject:index]) {
    CVCAbstractEntity *entity = [[self dataArray] objectAtIndex:row];
    NSString *name = [entity name];
    cellView = [tableView makeViewWithIdentifier:@"nameOnly" owner:self];
    [[cellView textField] setStringValue:name];

  } else if ([index integerValue] == CVCListPopUpIndexPublishers) {
    CVCPublisher *publisher = [[self dataArray] objectAtIndex:row];
    NSString *identifier = [tableColumn identifier];
    NSString *content;

    content = [[publisher valueForKeyPath:identifier] description];
    if ([identifier containsString:@"year"] && [content isEqualToString:@"0"]) {
      content = @"";
    }

    cellView = [tableView makeViewWithIdentifier:identifier owner:self];
    [[cellView textField] setStringValue:content ? content : @""];

  } else if ([index integerValue] == CVCListPopUpIndexSeries) {
    CVCSeries *series = [[self dataArray] objectAtIndex:row];
    NSString *identifier = [tableColumn identifier];
    NSString *content;

    content = [[series valueForKeyPath:identifier] description];
    if ([identifier containsString:@"year"] && [content isEqualToString:@"0"]) {
      content = @"";
    }

    cellView = [tableView makeViewWithIdentifier:identifier owner:self];
    [[cellView textField] setStringValue:content ? content : @""];
  }

  return cellView;
}

- (void)tableView:(NSTableView *)tableView sortDescriptorsDidChange:(NSArray *)oldDescriptors {
  NSMutableArray *mutableDataArray = [[self dataArray] mutableCopy];
  [mutableDataArray sortUsingDescriptors:[tableView sortDescriptors]];

  [self setDataArray:mutableDataArray];
  [[self nameOnlyTableView] reloadData];
}

It turns out that not only does the table column need to be editable, but the text field in the cell view does as well. Selecting this text field and selecting Editable from the Behavior menu solved the problem.