Ajp13 protocol

[Roberto B.]

I'm using a linux box.
I added this line in file server.xml

<RequestInterceptor
    className="org.apache.tomcat.modules.server.Ajp13Interceptor"
    port="8009"/>

to enable Ajp13 protocol, but when I start Tomcat 3.2.3 I receive an error.
Is it necessary the above line in order to activate Ajp13??

thanks!

Roberto.