unfortunately, app has stopped when trying to log into Facebook from mobile

I managed to incorporate the Facebook API into my project successfully, meaning, my game can take screenshots and post them into Facebook when clicking a button. However, this only works when running the application within the editor; touching that same button on my android device crashes the application instead (Unfortunately, appName has stopped).

I have been looking for a solution to this issue two days now, and while I came across a lot of different fixes, nothing seems to work; I already tried generating the correct hash key (with several different approaches), the apparently famous Rafael Fix, I tried fixing the screen orientation issue via AndroidManifest.xml, and I tried commenting the ScreenShot posting code (to make sure that Login is at fault).

I haven't made the app public on facebook, or uploaded to game to the play store yet (since it isnt ready for release yet anyways), but I don't think that should cause the game to crash like this.

I have a couple of days off my mandatory army service, and I really wanted to get this up and running before I had to go back to base. But, I am at my wit's end.

I'd really appreciate it if anyone could help me out with this.

Relevant Code:

   void Awake() {
 
         FB.Init(SetInit, OnHideUnity); 
     }
 
 
     private void SetInit() {
 
         print("FB: Init");
 
         if (FB.IsLoggedIn) print("FB: logged in");
 
         else print("FB: Not logged in");
     
     }
 
 
     public void FBLogin() {
 
         FB.LogInWithPublishPermissions(new List<string>() { "email", "publish_actions" }, AuthCallback);
         
     }
 
 
     void AuthCallback(ILoginResult result) {
 
         if (FB.IsLoggedIn) {
 
             print("FB: Login success");
             StartCoroutine(TakeScreenshot());
         }
 
         else print("FB: Login failure");
       
     }
 
 
 
     public void ShareScore() {
 
         if (!FB.IsLoggedIn) FBLogin();
     }
 
     
 
     private IEnumerator TakeScreenshot() {
 
         yield return new WaitForEndOfFrame();
         //print("W : " + Screen.width + " H : " + Screen.height); 
         var width = Screen.width;
         var height = Screen.height;
         var tex = new Texture2D(width, height, TextureFormat.RGB24, false);
 
         // Read screen contents into the texture
         tex.ReadPixels(new Rect(0, 0, width, height), 0, 0);
         tex.Apply();
         byte[] screenshot = tex.EncodeToPNG();
 
         var wwwForm = new WWWForm();
         wwwForm.AddBinaryData("image", screenshot, "InteractiveConsole.png");
         wwwForm.AddField("message", "herp derp.  I did a thing!  Did I do this right?");
         FB.API("me/photos", HttpMethod.POST, ShareCallback, wwwForm);
     }
     
 
 
     private void ShareCallback(IResult result) {
 
         if (result == null) {
 
             print("no result");     
             return;
         }
 
         // Some platforms return the empty string instead of null.
         if (!string.IsNullOrEmpty(result.Error)) print(result.ToString());
         
         else if (result.Cancelled) print("Cancelled");
         
         else if (!string.IsNullOrEmpty(result.RawResult)) print("Sucess, check log");
         
         else print("empty"); 
         
     }
 
 
     private void OnHideUnity(bool isGameShown) {
 
         print("FB: Hide Unity : " + !isGameShown);
        /* if (!isGameShown) Time.timeScale = 0;
         else Time.timeScale = 1;*/
     }