add images to UIBarButtonItem of toolbar in ios

add images to UIBarButtonItem of toolbar in ios

I have a UIBarButtonItem that does not take the picture
I have a toolbar with a button UIBarButtonItem above, connected via
IBOutlet. The image that I put you do not see. My code
@interface ViewController : {
IBOutlet UIToolbar *toolBar;
IBOutlet UIBarButtonItem * myBackButton;
IBOutlet UIBarButtonItem * myReloadButton;
IBOutlet UIBarButtonItem * myHomeButton;
IBOutlet UIBarButtonItem * myListButton;
IBOutlet UIBarButtonItem * myCalendarbutton;//the problem is this
}
the button is connect by IB but does not take the picture.
this is the image

this is the IB