With JSP2.1 the "#" character is used in the JSP EL. OGNL does use this escape character as well.
To get around this there is the possibility to disable JSP EL in web.xml:

related threads:

• http://www.mail-archive.com/user%40struts.apache.org/msg56749.html
• http://forums.opensymphony.com/thread.jspa?messageID=100059