iPhone FBConnect security captcha pages doesnt load

I use FBConnect provided for iPhone Facebook integration. When I try to post something to my wall it prompts me the security captcha page and it doesnt load the image to enter text. I use following dialog for this.

facebook = [[Facebook alloc] initWithAppId:kFacebook_APP_ID];
[facebook dialog:@"feed" andParams:params andDelegate:sel开发者_C百科f];

What can be the reason for this. Am I doing something wrong here?

Thank you