Sign in on SoundCloud using FaceBook not working on second Time

[bhupi012]

Hi

I Uploading audio file from my desktop app to SoundCloud It is working fine when I am logging for getting Access_token from my SoundCloud Account .

When user Start Desktop app then for first file he uploads to SC requiring sign in to SC then i save access token returned for avoiding sign-in process again .this process repeated for next app start.

I am getting non-expiring AccessToken
urlQuery.addQueryItem(LinAuthParameters::kLinAuthScope, "non-expiring");

Problem is when i am signing in with Facebook on SC

First i Create FB acc then sign in with FB on SC from my app it works for first time
but when i restart my app and again sign in with FB on SC from my app then qwebview windows show blank window after entering FB username Password

What i getting about problem is that

For sign in with Fb on SC non-expiring token is not returned again Problem is with token . It just returned once for first time sign in with Fb on SC from my app.

how to get expiring token and to check its if its expires on Oauth2.0

I am not getting how to solve it
any help