I wanted to access Google Play Developer API. This is what I am getting when I made a request to the API.

{
  "code" : 401,
  "errors" : [ {
    "domain" : "global",
    "location" : "Authorization",
    "locationType" : "header",
    "message" : "Invalid Credentials",
    "reason" : "authError"
  } ],
  "message" : "Invalid Credentials"
}

I followed these steps:

1. I created a sample project in google developer console.
2. Created OAuth client id, client secret and redirect URI.
3. I got code parameter from redirect URI.
4. Created refresh token and access token.

Any help??