UIBarButtonItem black instead of white

Question

I have that Navigation Controller and I'm adding 1 button by code this way:

UIBarButtonItem *configButton = [[UIBarButtonItem alloc] initWithImage:[UIImage imageNamed:@"config.png"] style:UIBarButtonItemStyleBordered target:self action:@selector(showConfigWindow)]; 
self.navigationItem.leftBarButtonItem = configButton;

It's working right but the icons are black instead of white!!

If I use this:

UIBarButtonItem *configButton = [[UIBarButtonItem alloc] initWithTitle:@"Settings" style:UIBarButtonItemStyleBordered target:self action:@selector(showConfigWindow)];

The text is showed properly in white.

The icons are ok cause I'm using them through interface builder and they show right.