The request requires user authentication. The response MUST include a WWW-Authenticate header field containing a challenge applicable to the requested resource.

The client MAY repeat the request with a suitable Authorization header field. If the request already included Authorization credentials, then the 401 response indicates that auhorization has been refused for those credentials. If the 401 response contains the same challenge as the prior response, and the user agent has already attempted authentication at least once, then the user SHOULD be presented the entity that was given in the response, since that entity might include relevant diagnostic information.

Check your username for typographical errors, and check that you are using the correct capitalization for your password (e.g. check that the CapsLock setting on your keyboard is appropriate). It is possible that an error in the address has led you from a page that doesn't require authentication to one that does. If you monitor your website through 100pulse, we will intimate you whenever you encounter 401 status code errors through e-mail or Short message service.