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

[keewks]

Here's my problem:
When I load a jsp file (servername:8080/examples/jsp/num/numguess.jsp) such as numguess.jsp in Tomcat's examples everything is ok, the class is compiled. Then if I remove class in the Tomcat's work directory and I load numguess.jsp with Apache (servername:80/ examples/jsp/num/numguess.jsp) I have this error:

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

An error occurred at line: -1 in the jsp file: null

Generated servlet error:

[javac] Compiling 1 source file

at org.apache.jasper.compiler.DefaultErrorHandler.javacError(DefaultErrorHandler.java:130) at org.apache.jasper.compiler.ErrorDispatcher.javacError(ErrorDispatcher.java:293) at org.apache.jasper.compiler.Compiler.generateClass(Compiler.java:340) at org.apache.jasper.compiler.Compiler.compile(Compiler.java:352) at org.apache.jasper.JspCompilationContext.compile(JspCompilationContext.java:474) at org.apache.jasper.servlet.JspServletWrapper.service(JspServletWrapper.java:184) at org.apache.jasper.servlet.JspServlet.serviceJspFile(JspServlet.java:295) at org.apache.jasper.servlet.JspServlet.service(JspServlet.java:241) at javax.servlet.http.HttpServlet.service(HttpServlet.java:853)...
...

If I start Tomcat, and Apache, and I load servername:80/examples/jsp/num/numguess.jsp then this class is compiled.

Does anybody know why I have this error? :-(