Error getting authorization token

Hi everyone, I have a problem with the Twitch API. When I call https://api.twitch.tv/kraken/user with my personal Twitch account authenticated it works flawlessly. But then I created a new Twitch account to test it with another account and there I run into problems. The code is exactly the same but returns this as a response:
user did load: {
“message” : “error getting authorization token”,
“status” : 401,
“error” : “Unauthorized”
}
The exact same scopes are in place and when I call https://api.twitch.tv/kraken to check the auth status it shows everything correctly… Is there some Sandbox like restriction so that I can’t test it with another Twitch account other than the one that created the app or what is the problem here?
I hope somebody can help me
kind regards,
Marc

Can we see the code you are using with the secrets removed?