Hibernate version: 2.1.7c

this is my mapping file
Person.hbm.xml
<?xml version="1.0"?>
<!DOCTYPE hibernate-mapping
PUBLIC "-//Hibernate/Hibernate Mapping DTD//EN"
"http://hibernate.sourceforge.net/hibernate-mapping-2.0.dtd">

<hibernate-mapping>

<class name="onlyfun.caterpillar.User" table="USER">

<id name="id" type="string" unsaved-value="null">
<column name="user_id" sql-type="char(32)"/>
<generator class="uuid.hex"/>
</id>

<property name="name" type="string" not-null="true">
<column name="name" length="16" not-null="true"/>
</property>

<property name="sex" type="char" />

<property name="age" type="int"/>

</class>

</hibernate-mapping>

then this is my build.xml file
build.xml
<project name="Hibernate" default="schema" basedir=".">
<property name="source.root" value="src"/>
<property name="class.root" value="classes"/>
<property name="lib.dir" value="lib"/>
<property name="data.dir" value="data"/>

<path id="project.class.path">
<!-- Include our own classes, of course -->
<pathelement location="${class.root}" />
<!-- Include jars in the project library directory -->
<fileset dir="${lib.dir}">
<include name="*.jar"/>
</fileset>
<pathelement path ="${classpath}"/>
</path>

<target name="schema" description="Generate DB schema from the O/R mapping files">
<!-- Teach Ant how to use Hibernate's schema generation tool -->
<taskdef name="schemaexport"
classname="net.sf.hibernate.tool.hbm2ddl.SchemaExportTask"
classpathref="project.class.path"/>

<schemaexport properties="${source.root}/hibernate.properties"
quiet="no" text="no" drop="no" delimiter=";">
<fileset dir="${source.root}">
<include name="**/*.hbm.xml"/>
</fileset>
</schemaexport>
</target>
</project>

then upon typing ant, this is the error i encountered
schema
build failed
java.lang.NoClassDefFoundError: org/dom4j/Attribute at net.sf.hibernate.tool.hbm2ddl.SchemaExportTask.getConfiguration(SchemaExportTask.java:182)
...

what seems to be the problem?
could any one lend a help on me~

tnkx

problem sovled
setting classpath for the libraries does not solve that problem
what i did was putting the required hibernate jars into ant's lib
then it worked...

grr... it successfully build... but it does not reflect on the database...
no table added ...
how come?
any one know why?