How to share image in persistentDataPath to facebook feed?

I'm trying to share an image taking from CaptureScreenshot() using FB.ShareLink(...) to Facebook.

My code is the following: (After calling FB.Init(), etc..)

  string tmpScreenshotPathname = "file:///" + currentScreenshotPathname;
  System.Uri contentUri = new System.UriBuilder(tmpScreenshotPathname).Uri;
  System.Uri imageUri = new System.UriBuilder(tmpScreenshotPathname).Uri;
  FB.ShareLink(contentUri, "Test", "Test desc", imageUri);

However, when open the FB share, the page opens for a split second before returning me back to the game. I tried using a normal Uri such as http://........jpg and it works fine, but when I try to use a local Uri, it fails.

Is there any way to share the image to the feed without uploading it to the user's Facebook gallery using FB.API? Because there's the case where the user might decide not to share the image to the feed.. but it would have already been uploaded to his gallery from FB.API.