Thanks for the answer.
The problem is that I was assigned the code (which is from someone I don't know) and have no idea where package "com.ms.xml.om" is. I guess it is somewhere under "classes" directory, so I do include "src", "classes", "lib" and other possible "lib". Sorry if this is a stupid question.
<path id="project.class.path">
<pathelement location="/usr/local/java/ant/lib/"/>
<pathelement location="/home/www/semwebjournal/tomcat/common/lib/"/>
<pathelement location="${build}" />
<pathelement location="classes/"/>
<pathelement location="src/"/>
<pathelement location="lib/"/>
<fileset dir="/usr/local/java/ant/lib">
<include name="**/*.jar"/>
</fileset>
<fileset dir="/home/www/semwebjournal/tomcat/common/lib">
<include name="**/*.jar"/>
</fileset>
<fileset dir="classes">
<include name="**/*.class"/>
</fileset>
<fileset dir="src">
<include name="**/*.java"/>
</fileset>
<fileset dir="lib">
<include name="**/*.jar"/>
</fileset>
</path>
and compile like this,
<target name="compile" depends="init"
description="compile the source " >
<!-- Compile the java code from ${src} into ${build} -->
<javac srcdir="${src}" destdir="${build}" debug="true" precation="true">
<classpath refid="project.class.path"/>
</javac>
</target>
