Problem with JSP

[daveisme]

Hi guys
I'm new at JSP, and I've to run an ex-collegue software.

It's Java + JSP, usin' Apache Tomcat. When I run Tomcat and I try to open the Default.jsp page, here's what appears:

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HTTP Status 500 - 
type Exception report

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: 

An error occurred at line: 6 in the generated java file
Only a type can be imported. Extenders.SessionExtender resolves to a package

An error occurred at line: 53 in the jsp file: /WebContent/Default.jsp
SessionExtender cannot be resolved
50: </body>	
51: <%
52: 	//on unload page 
53:     SessionExtender.getSessionExtender(session).getErrorBean().setUrlTyped("Default.jsp"); 
54: %>
55: </html>


Stacktrace:
	org.apache.jasper.compiler.DefaultErrorHandler.javacError(DefaultErrorHandler.java:95)
	org.apache.jasper.compiler.ErrorDispatcher.javacError(ErrorDispatcher.java:330)
	org.apache.jasper.compiler.JDTCompiler.generateClass(JDTCompiler.java:457)
	org.apache.jasper.compiler.Compiler.compile(Compiler.java:367)
	org.apache.jasper.compiler.Compiler.compile(Compiler.java:345)
	org.apache.jasper.compiler.Compiler.compile(Compiler.java:332)
	org.apache.jasper.JspCompilationContext.compile(JspCompilationContext.java:594)
	org.apache.jasper.servlet.JspServletWrapper.service(JspServletWrapper.java:342)
	org.apache.jasper.servlet.JspServlet.serviceJspFile(JspServlet.java:391)
	org.apache.jasper.servlet.JspServlet.service(JspServlet.java:334)
	javax.servlet.http.HttpServlet.service(HttpServlet.java:722)

Note: The full stack trace of the root cause is available in the Apache Tomcat/7.0.6 logs.

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I really don't know which error is...
Does some of you have an idea of what could be the problem?

Thank you very much! :-)