navigation bar image hiding custom navigation bar button

I am able to give image to navigation bar and also changed image of navigation bar button item. For some reason navigation bar image, i guess, overlapped over navigation bar button image. Navigation bar button is functioning right when i click on navigation bar image at left but its not displaying over navigation bar image. here is the code ;

UIImage *imagebar = [UIImage imageNamed: @"schedule-strip.png"];
 UIImageView *imageView = [[UIImageView alloc] initWithImage: imagebar];
 imageView.frame = CGRectMake(0, 0, 190, 44);
 imageView.contentMode = UIViewContentModeScaleAspectFill;
 self.navigationItem.titleView = imageView;
 
 
 UIImage* image = [UIImage imageNamed:@"back-icon.png"];
 CGRect frame = CGRectMake(0, 0, image.size.width, image.size.height);
 UIButton* someButton = [[UIButton alloc] initWithFrame:frame];
 [someButton setBackgroundImage:image forState:UIControlStateNormal];
 [someButton setShowsTouchWhenHighlighted:YES];
 [someButton addTarget:self action:@selector(backToMore) forControlEvents:UIControlEventTouchUpInside];
 
 UIBarButtonItem* someBarButtonItem = [[UIBarButtonItem alloc] initWithCustomView:someButton];
 [self.navigationItem setLeftBarButtonItem:someBarButtonItem];
 
 [someBarButtonItem release];
 [someButton release]; 
 

help me out.

---