Why is an empty string returned when trying to get an access_token?

Question

API

1. I send the user to https://connect.ok.ru/oauth/authorize with all parameters: Link .
2. I get the code when the user goes to redirect_uri.
3. I send the user to https://api.odnoklassniki.ru/oauth/token.do .
4. Dumping the response, I get string(0) "". That is, an empty answer. But if I make a request, for example, through hurl.it, then I get a token in the response body.
What am I doing wrong?
Application: ok.ru/game/1236194560
Website: dev.csgovictory.com/ru (Authorization is at the top right)

Answer 1

1. Check the headers - are you sure you are sending everything?
2. Write in the TP.