为什么错误？ - 从Facebook SDK iOS Share Dialog发布照片

Question

我将照片发布到Facebook，为什么会出错？

-facebook iOS SDK ver 3.19
-facebook App ver 17.0
-iOS ver -iOS7.1.2 -iOS8.0

BOOL canPresent = [FBDialogs canPresentShareDialogWithPhotos];

FBPhotoParams *params = [[FBPhotoParams alloc] init];
params.photos = @[targetImage];

BOOL isSuccessful = NO;
if (canPresent) {
    FBAppCall *appCall = [FBDialogs presentShareDialogWithPhotoParams:params
                                                          clientState:nil
                                                              handler:^(FBAppCall *call, NSDictionary *results, NSError *error) {

                                                                  if (error) {
                                                                      NSLog(@"Error: %@", error.description);
                                                                  } else {
                                                                      NSLog(@"Success!");
                                                                  }
                                                              }];
    isSuccessful = (appCall  != nil);

可以发布到Facebook的照片。但是，始终会返回错误。

Error: Error Domain=com.facebook.Facebook.platform Code=103 "The operation couldn’t be completed. (com.facebook.Facebook.platform error 103.)" UserInfo=0x1782e3a00 {error_reason=(
    {
    result = 1;
}
), error_description=An unknown error occurred., app_id=434867889904974, error_code=103}

为什么返回错误？
这个错误，忽略OK？