login LTM fail via restful API

I try to login a LTM , but it returns an error below:

{'code': 401, 'message': 'remoteSender:http://localhost:8100/shared/authn/login, method:POST ', 'originalRequestBody': '{"username":"AAAAA","loginProviderName":"tmos","generation":0,"lastUpdateMicros":0}', 'referer': '11111', 'restOperationId': 123326437, 'kind': ':resterrorresponse'}

the username and password are correct , I can login via browser , I can also login the another device by restful API with the same code . so what is problem it could be.