can't display custom BarButton on toolbar

I used the following codes to the ZBar Reader Sample source code, then create a libzbar.a and added to my iOS App.But can't display custom BarButton on toolbar. Please help. thanks!
 
`ZBarReaderViewController.h
 
@interface ZBarReaderViewController: UIViewController
{IBOutlet UIButton *PowerButton;}
 
@property (nonatomic, assign) IBOutlet UIButton *PowerButton;
 
ZBarReaderViewController.m
 
@synthesize PowerButton;
 
CGRect frame1 = CGRectMake(150.0, 435.0, 50.0, 10.0);
PowerButton = [[UIButton alloc] initWithFrame:frame1];
UIImage *chatImage = [UIImage imageNamed:@"PowerButtonOn.png"];
PowerButton = [UIButton buttonWithType:UIButtonTypeCustom];
[PowerButton setImage:[UIImage imageNamed:@"PowerButtonOn.png"] forState:UIControlStateNormal];
[PowerButton setImage:[UIImage imageNamed:@"PowerButtonOff.png"] forState:UIControlStateSelected];
[PowerButton setBackgroundImage:chatImage forState:UIControlStateNormal];
[PowerButton addTarget:self action:@selector(PowerButtonPressed:) forControlEvents:UIControlEventTouchUpInside];
toolbar.items =[NSArray arrayWithObjects:[[[UIBarButtonItem alloc]
    initWithBarButtonSystemItem: UIBarButtonSystemItemCancel
    target: self
    action: @selector(cancel)]
    autorelease],
    [[[UIBarButtonItem alloc]
    initWithBarButtonSystemItem: UIBarButtonSystemItemFlexibleSpace
    target: nil
    action: nil]
    autorelease],
    [[[UIBarButtonItem alloc] initWithCustomView:PowerButton] autorelease],
    [[[UIBarButtonItem alloc]
    initWithBarButtonSystemItem: UIBarButtonSystemItemFlexibleSpace
    target: nil
    action: nil]
    autorelease], nil];
[controls addSubview: toolbar];
    [toolbar release];
[view addSubview: controls];`

补充：移动开发 ,  iPhone