title: Getting problem to wall post on Facebook
body: <p>When I login to Facebook through my app, everything works, but I'm having problems posting to walls.</p>
  
  <pre><code>- (NSString *) postToFBWallStatus:(NSString *) status andSetDelegate: (id) delegate
  {
      if (! isFBLoggedIn) 
      {
          return @"NotLoggedin";
      }
  
      NSString *message = status;
      NSLog(@"Appdelegate: postToFBWallStatus:andSetDelegate:");
      NSLog(@"to be delegate class: %@",[delegate class]);
  
      NSURL *url = [NSURL URLWithString:@"https://graph.facebook.com/me/feed"];
  
      ASIFormDataRequest *newRequest = [ASIFormDataRequest requestWithURL:url];
      [newRequest setPostValue:message forKey:@"message"];
      [newRequest setPostValue:@"" forKey:@"name"];
      [newRequest setPostValue:@"" forKey:@"caption"];
      [newRequest setPostValue:@"" forKey:@"description"];
      [newRequest setPostValue:@"" forKey:@"link"];
      [newRequest setPostValue:@"" forKey:@"picture"];
      [newRequest setPostValue:_accessToken forKey:@"access_token"];
      [newRequest setDidFinishSelector:@selector(postToWallFinished:)];
      [newRequest setDidFailSelector:@selector(postToWallFailed:)];
      [newRequest setDelegate:delegate];
      [newRequest startAsynchronous];
  
      return @"Loggedin";
  }
  </code></pre>
  
  <p>I get this message when I post to the Facebook wall:</p>
  
  <pre><code>error =     {
          message = "Invalid access token signature.";
          type = OAuthException;
      };
  </code></pre>