error unsupported grant type is returned when sending post request with x-www-form-urlencoded

Question

keywords.user_loads_a_Request("AdminLogin", CONFIG.getProperty("URI")+"api/login"); // Adminlogin file contains the request

keywords.user_posts_request("POST");

keywords.user_addsHeader("Content-Type", "x-www-form-urlencoded");  

keywords.user_addsHeader("charset", "utf-8");

keywords.user_loads_a_Request(URLEncoder.encode("grant_type=password&username=example%40live.com&password=Password2%40&isfflogin=false"),"UTF-8");