Building Tomcat 5.5 from SVN problem

I was attempting to build Tomcat 5.5 from SVN using the instructions from tomcat pages, however I was getting an error of: /home/buckett/src/tomcat/build.xml:49: The following error occurred while executing this line: /home/buckett/src/tomcat/build/build.xml:791: The following error occurred while executing this line: /home/buckett/src/tomcat/container/webapps/docs/build.xml:88: java.lang.ClassNotFoundException: org.apache.tools.ant.taskdefs.optional.TraXLiaison after a little head scratching I discovered that I had installed ant as an Ubuntu package and I was missing the ant-optional package which provided this extra functionality. After intalling this additional package everything went smoothly.