I am also using the same Lazy Image Loader.I think you are not passing the context correctly.
int loader = R.drawable.loader;//Old image in the imageview
ImageLoader imgLoader = new ImageLoader(ctx); // ctx is the context
imgLoader.DisplayImage(image_url, loader, image);//image is the imageview,image_url is the url to image
Check out my output.If you still needs any help i am attaching my sample.Download it.Check out the link