Confusing tomcat error - can't find javax.servlet.http.HttpSessionAttributeListener

[glitch003]

Hi, I'm getting a fatal error when I start tomcat. Now I would think that servlet-api.jar is missing from the tomcat classpath but if I do -verbose:class I can clearly see tomcat using other classes from that jar so I know it's already included:

[Loaded javax.servlet.http.HttpServletRequest from file:/C:/Program%20Files/Apache%20Software%20Foundation/Tomcat%206.0/lib/servlet-api.jar]


The exact error I'm getting is:

java.lang.Error: Unresolved compilation problems:
The import javax.servlet.http.HttpSessionAttributeListener cannot be resolved
The import javax.servlet.http.HttpSessionBindingEvent cannot be resolved
HttpSessionAttributeListener cannot be resolved to a type
HttpSessionBindingEvent cannot be resolved to a type
HttpSessionBindingEvent cannot be resolved to a type
HttpSessionBindingEvent cannot be resolved to a type
HttpSessionBindingEvent cannot be resolved to a type


The file that gives this error has import javax.servlet.http.*; at the top so it appears that I've already imported the necessary classes. How can I fix this fatal error? Why does tomcat see javax.servlet.http.HttpServletRequest but not javax.servlet.http.HttpSessionAttributeListener?

Thank you