JDK与tomcat的一个奇怪的问题 问了N多人都不知道 ？
我安装完JDK1.5   ,且配置好后，用   helloword.java   程序测试正常
然后安装完tomcat5.0.28   且配置好后，输入   http://localhost:8080/   也能得出正常运行的画面（带猫的那个画面）。
具体的配置：
classpath         .;C:\Program   Files\Java\jdk1.5.0_04\lib\dt.jar;C:\Program   Files\Java\jdk1.5.0_04\lib\tools.jar

PATH             C:\Program   Files\Java\jdk1.5.0_04\bin;C:\Program   Files\Java\jdk1.5.0_04\lib

JAVA_HOME         C:\Program   Files\Java\jdk1.5.0_04

CATALINA_HOME         C:\Tomcat   5.0

但是我运行   JSP   页面的时候   能报如下错误   ：
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   compile   class   for   JSP
org.apache.jasper.compiler.DefaultErrorHandler.javacError(DefaultErrorHandler.java:97)
org.apache.jasper.compiler.ErrorDispatcher.javacError(ErrorDispatcher.java:346)
org.apache.jasper.compiler.Compiler.generateClass(Compiler.java:414)
org.apache.jasper.compiler.Compiler.compile(Compiler.java:472)
org.apache.jasper.compiler.Compiler.compile(Compiler.java:451)
org.apache.jasper.compiler.Compiler.compile(Compiler.java:439)
org.apache.jasper.JspCompilationContext.compile(JspCompilationContext.java:511)
org.apache.jasper.servlet.JspServletWrapper.service(JspServletWrapper.java:295)
org.apache.jasper.servlet.JspServlet.serviceJspFile(JspServlet.java:292)
org.apache.jasper.servlet.JspServlet.service(JspServlet.java:236)
javax.servlet.http.HttpServlet.service(HttpServlet.java:802)


root   cause  

Unable   to   find   a   javac   compiler;
com.sun.tools.javac.Main   is   not   on   the   classpath.
Perhaps   JAVA_HOME   does   not   point   to   the   JDK
org.apache.tools.ant.taskdefs.compilers.CompilerAdapterFactory.getCompiler(CompilerAdapterFactory.java:106)
org.apache.tools.ant.taskdefs.Javac.compile(Javac.java:935)
org.apache.tools.ant.taskdefs.Javac.execute(Javac.java:764)
org.apache.jasper.compiler.Compiler.generateClass(Compiler.java:382)
org.apache.jasper.compiler.Compiler.compile(Compiler.java:472)
org.apache.jasper.compiler.Compiler.compile(Compiler.java:451)
org.apache.jasper.compiler.Compiler.compile(Compiler.java:439)
org.apache.jasper.JspCompilationContext.compile(JspCompilationContext.java:511)
org.apache.jasper.servlet.JspServletWrapper.service(JspServletWrapper.java:295)
org.apache.jasper.servlet.JspServlet.serviceJspFile(JspServlet.java:292)
org.apache.jasper.servlet.JspServlet.service(JspServlet.java:236)
javax.servlet.http.HttpServlet.service(HttpServlet.java:802)


note   The   full   stack   trace   of   the   root   cause   is   available   in   the   Apache   Tomcat/5.0.28   logs.


哪位高手能够指导一下   ，为什么   ？     是不是版本问题引起的  
tomcat5.0.28+j2sdk1.5

谢谢了  


------解决方案--------------------
com.sun.tools.javac.Main is not on the classpath.
Perhaps JAVA_HOME does not point t