我自定义accessoryButton的图片，但是Delegate么有响应，哪弄错了？

UIImage *accessoryImage = [UIImage imageNamed:@"acc_bg.png"];
UIImageView *accImageView = [[UIImageView alloc] initWithImage:accessoryImage];
accImageView.userInteractionEnabled = YES;
[accImageView setFrame:CGRectMake(0, 0, 28.0, 28.0)];
self.accessoryView = accImageView;
[accImageView release];

tableView:accessoryButtonTappedForRowWithIndexPath: 没有响应