When off campus, the best way to access Web of Science is through the library's database page: Web of Science
If you are using a bookmark you created on campus, you may not be going through the off-campus proxy server which assigns you a temporary IP address that allows vendors to recognize you as affiliated with ESF. The proxied URL is https://esf.idm.oclc.org/login?url=http://webofknowledge.com/WOS
