retrieve Facebook app request ID from FB.GetAppLink result callback

Hello ,
i'm wondering what is the best way to retrieve an app request ID from an Iapp link result , i use unity facebook sdk , and when i use the code provided in facebook documentation section , this one i mean
https://developers.facebook.com/…/ref…/current/FB.GetAppLink

Code (CSharp):

1. FB.GetAppLink(DeepLinkCallback);
2.  
3. void DeepLinkCallback(IAppLinkResult result) {
4. if(!String.IsNullOrEmpty(result.Url)) {
5. var index = (new Uri(result.Url)).Query.IndexOf("request_ids");
6. Debug.Log("index "+index );
7. if(index != -1) {
8. //
9. }
10. }
11. }

i get index =-1
i have attached an image of what result.RawResult looks like ,
please i need some help

 

up !!