JSP problem with tomcat: can't find set method

[Eckhard Beisswenger]

I receive an error in a jsp application when it's running with tomcat, though the error doesn't occur with WebLogic.
The JSP uses a bean called "porto.tachart.DBConnect" which contains a property called "authentication" and the corresponding set method:
public void setAuthentication(HttpServletRequest request) {
authentication = checkAuth(request);
// the checkAuth method works fine
}
However, tomcat won't find the set method for "authentication" (though other set methods which are called earlier are found). tomcat throws this error message:
org.apache.jasper.JasperException: Can't find a method to write property 'authentication' in a bean of type 'porto.tachart.DBConnect'
at org.apache.jasper.runtime.JspRuntimeLibrary.handleSetProperty(Unknown Source)
at index_4._jspService(index_4.java, Compiled Code)
at org.apache.jasper.runtime.HttpJspBase.service(Unknown Source)
at javax.servlet.http.HttpServlet.service(HttpServlet.java, Compiled Code)
at org.apache.tomcat.facade.ServletHandler.doService(Unknown Source)
at org.apache.tomcat.core.Handler.invoke(Unknown Source)
at org.apache.tomcat.core.Handler.service(Unknown Source)
at org.apache.tomcat.facade.ServletHandler.service(Unknown Source)
at org.apache.tomcat.core.ContextManager.internalService(Unknown Source)
at org.apache.tomcat.core.ContextManager.service(Unknown Source)
at org.apache.tomcat.modules.server.Http10Interceptor.processConnection(Unknown Source)
at org.apache.tomcat.util.net.TcpWorkerThread.runIt(Unknown Source)
at org.apache.tomcat.util.threads.ThreadPool$ControlRunnable.run(Unknown Source)
at java.lang.Thread.run(Thread.java, Compiled Code)
I'll be glad for any help. Many thanks in advance,
Eckhard Beisswenger