API authentication using other extension

Hi, We are trying to authenticate RC credentials using the API. Our RC account has 2 extension numbers. Using the first extension, we are able to authenticate the credentials but using the other one, it resulted to a bad request: HTTP/1.1 400 Bad Request Server: nginx/1.8.0 Date: Fri, 23 Sep 2016 10:30:04 GMT Content-Type: application/json;charset=UTF-8 Content-Length: 49 Connection: keep-alive RCRequestId: b106d9be-8178-11e6-b3aa-005056979a38 RoutingKey: IAD01P08PAS01 Content-Language: en X-AGW-Host: sjc01-c01-agw01.c01.ringcentral.com { "message" : "Bad Request", "errors" : [ ] } Anybody knows what is wrong? We are able to login successfully using that other extension in the Ringcentral site with the same password entered as to the API.