Could not get the API work

[Steven-G84]

Hello together,

sorry for my english, not my native language ;-)

I am not able to get the Viessmann API to work and i not know why. Maybe some of you can get me an advice?
I edited the credentials file with my username, pwd and the clientid.
when i open the main.php this is the error:

Message: Error during authentication process. Please review your username/password Code: 0 Message: response didn't contains code to get token probably due to an error in authentication process. Response :
400 Bad Request

username and password is correct, vicare app and so on works fine. So what am i doing wrong...?

Best regards,

Steven