如何结合Tomcat 5.5使用logback-access？

I've got several Web apps running on a Tomcat 5.5 server, and I'm working on improving/updating the overall logging system used throughout the system. I already had some success with logback-classic. However, when I try to use logback-access (i.e. access the lbAccessStatus servlet), I get this exception:I've got several Web apps running on a Tomcat 5