Unable to get Access token using Postman

dp
Community Explorer

I am unable to get the access token when I post a request using Postman. I am receiving the authorization code from the browser and passing the authorization in the Postman request. I have attached screenshot and I am receiving HTTP status as 400 Bad Request with a message 

{
    "error""invalid_grant",
    "error_description""authorization_code not found"
}

 

Do you have any idea what am I doing wrong here?

Canvas Postman.JPG