Not getting url thumbnail image

[intersilindia]

Code Snippet:

[MTDURLPreview loadPreviewWithURL:[NSURL URLWithString:@"http://www.skype.com/en/"]
completion:^(MTDURLPreview *preview, NSError *error){

                          [self.imgPreview setFromURLPreview:preview];

                           NSLog(@"check the image path %@",preview.imageURL);
                       }];

I am unable to fetch thumbnail image for the url.
Please provide me inputs here

Thanks in advance