iOS Facebook Publish Feed Dialog doesn't show up after authentication

Question

Thanks for reading.

I went through Facebook iOS SDK Feed Dialog issue after authentication but in vain.

What works: I created a sample "Hello, World" app using the Facebook iOS Tutorial with the Feed Dialog. This tutorial works fine and I am able to see the post in my feed.

Problem: When I integrated this code in my app, I don't get to see the Feed Dialog after the authentication when the control reaches back to my app.

Flow of control: I have a UIImagePickerController showing a camera that takes a picture, then shows UIAlertView to indicate that the image is being uploaded, shows a UIAlertView to display the result returned from server, and then finally shows a UIActionSheet to display the different sharing options (share to Facebook, Twitter, etc.).

When the user hits "Share to Facebook", the following selector gets invoked:

- (void) initFacebook
{
    //Init Facebook
    facebook = [[Facebook alloc] initWithAppId:@"308136969223987" andDelegate:self];

    //Check for access_token 
    NSUserDefaults *defaults = [NSUserDefaults standardUserDefaults];
    if([defaults objectForKey:@"FBAccessTokenKey"]
       && [defaults objectForKey:@"FBExpirationDateKey"]) {
        facebook.accessToken = [defaults objectForKey:@"FBAccessTokenKey"];
        facebook.expirationDate = [defaults objectForKey:@"FBExpirationDateKey"];
    }

    if(![facebook isSessionValid]) {
        [facebook authorize:nil];
    }

    NSMutableDictionary* params = [NSMutableDictionary dictionaryWithObjectsAndKeys:
  kAppId, @"app_id",
  @"https://developers.facebook.com/docs/reference/dialogs/", @"link",
  @"http://fbrell.com/f8.jpg", @"picture",
  @"Facebook Dialogs", @"name",
  @"Reference Documentation", @"caption",
  @"Using Dialogs to interact with users.", @"description",
  @"Facebook Dialogs are so easy!",  @"message",
  nil];

  [_facebook dialog:@"feed" andParams:params andDelegate:self];  
}

This launches the Facebook app to authenticate, and then opens my app again with the UIImagePickerController but doesn't show the Feed Dialog.

Can someone please help me out?