Cannot build jsp pages

[Revenge]

hi all,
i've a JBuilder project with some packages and some jsp pages using these
packages.
When i try to build the project , there aren't errors or warnings but the
jsp pages are not built because there aren't the java files generated
(example index_jsp.java)
If I try to load the main jsp page from JBuilder it seems to work (even if
the index_jsp.java, etc....are not visible in project) but if I build a War
file and I deploy it under Tomcat 5.5, my browser says:
HTTP Status 500 -

----------------------------------------------------------------------------
----

type Exception report

message

description The server encountered an internal error () that prevented it
from fulfilling this request.

exception

org.apache.jasper.JasperException: Unable to load class for JSP

org.apache.jasper.JspCompilationContext.load(JspCo mpilationContext.java:591)

org.apache.jasper.servlet.JspServletWrapper.getSer vlet(JspServletWrapper.jav
a:137)

org.apache.jasper.servlet.JspServletWrapper.servic e(JspServletWrapper.java:3
08)
org.apache.jasper.servlet.JspServlet.serviceJspFil e(JspServlet.java:295)
org.apache.jasper.servlet.JspServlet.service(JspSe rvlet.java:245)
javax.servlet.http.HttpServlet.service(HttpServlet .java:802)

root cause

java.lang.ClassNotFoundException: org.apache.jsp.admin_jsp
java.net.URLClassLoader$1.run(Unknown Source)
java.security.AccessController.doPrivileged(Native Method)
java.net.URLClassLoader.findClass(Unknown Source)
org.apache.jasper.servlet.JasperLoader.loadClass(J asperLoader.java:158)
org.apache.jasper.servlet.JasperLoader.loadClass(J asperLoader.java:71)

org.apache.jasper.JspCompilationContext.load(JspCo mpilationContext.java:589)

org.apache.jasper.servlet.JspServletWrapper.getSer vlet(JspServletWrapper.jav
a:137)

org.apache.jasper.servlet.JspServletWrapper.servic e(JspServletWrapper.java:3
08)
org.apache.jasper.servlet.JspServlet.serviceJspFil e(JspServlet.java:295)
org.apache.jasper.servlet.JspServlet.service(JspSe rvlet.java:245)
javax.servlet.http.HttpServlet.service(HttpServlet .java:802)

note The full stack trace of the root cause is available in the Apache
Tomcat/5.5.7 logs.

Could you help me?
thanks in advance, Revenge