antlib.xml not found

Hi,

I followed the tutorial http://sardes.inrialpes.fr/~jphilipp...b3/index.xhtml
on the followingarchitecture:
ubuntu 8.10
Apache Ant version 1.7.1 compiled on October 3 2008
Java(TM) SE Runtime Environment (build 1.6.0_10-b33)
JOnAS 4.8.5 w/ Tomcat 5.5.17

I am in the 5th step (ant war ejb) and I have a build failed.
the error log is the following
thanks!!

init:
unpack:
[typedef] Could not load definitions from resource org/objectweb/easybeans/ant/antlib.xml. It could not be found.

compile:
[javac] Compiling 65 source files to /rubis/build
[javac] /rubis/src/edu/rice/rubis/beans/BidBean.java:4: package javax.persistence does not exist
[javac] import javax.persistence.*;
[javac] ^
[javac] /rubis/src/edu/rice/rubis/beans/BidBean.java:29: cannot find symbol
[javac] symbol: class Entity
[javac] @Entity
[javac] ^
[javac] /rubis/src/edu/rice/rubis/beans/BidBean.java:30: cannot find symbol
[javac] symbol: class Table
[javac] @Table(name="bids")
[javac] ^
[javac] /rubis/src/edu/rice/rubis/beans/UserBean.java:5: package javax.persistence does not exist
[javac] import javax.persistence.*;
[javac] ^
[javac] /rubis/src/edu/rice/rubis/beans/UserBean.java:6: package javax.persistence does not exist
[javac] import javax.persistence.NamedQuery;
[javac] ^
[javac] /rubis/src/edu/rice/rubis/beans/UserBean.java:32: cannot find symbol
[javac] symbol: class Entity......etc