Problemas en EJB

[Jesus =)]

Podrian ayudarme por aqui no entiendo en que me equivoque ...que
quiere decir este error la s referencias de los ejb en web.xml las
hices con ayuda del wizard

<?xml version = '1.0' encoding = 'windows-1252'?>
<!DOCTYPE ejb-jar PUBLIC "-//Sun Microsystems, Inc.//DTD Enterprise
JavaBeans 2.0//EN" "http://java.sun.com/dtd/ejb-jar_2_0.dtd">
<ejb-jar>
<enterprise-beans>
<entity>
<description>Entity Bean ( BMP )</description>
<display-name>UpdateEmployee</display-name>
<ejb-name>UpdateEmployee</ejb-name>
<home>businesstier.UpdateEmployeeHome</home>
<remote>businesstier.UpdateEmployee</remote>
<ejb-class>businesstier.impl.UpdateEmployeeBean</ejb-class>
<persistence-type>Bean</persistence-type>
<prim-key-class>businesstier.UpdateEmployeePK</prim-key-class>
<reentrant>False</reentrant>
<resource-ref>
<res-ref-name>jdbc/hrDS</res-ref-name>
<res-type>javax.sql.DataSource</res-type>
<res-auth>Application</res-auth>
</resource-ref>
</entity>
<session>
<description>Session Bean ( Stateless )</description>
<display-name>Employee</display-name>
<ejb-name>Employee</ejb-name>
<home>businesstier.EmployeeHome</home>
<remote>businesstier.Employee</remote>
<ejb-class>businesstier.impl.EmployeeBean</ejb-class>
<session-type>Stateless</session-type>
<transaction-type>Container</transaction-type>
</session>
</enterprise-beans>
</ejb-jar>

<?xml version = '1.0' encoding = 'windows-1252'?>
<!DOCTYPE orion-ejb-jar PUBLIC "-//Evermind//DTD Enterprise JavaBeans
1.1 runtime//EN" "http://xmlns.oracle.com/ias/dtds/orion-ejb-jar.dtd">
<orion-ejb-jar>
<enterprise-beans>
<entity-deployment max-instances="-1" name="UpdateEmployee"/>
<session-deployment max-instances="-1" name="Employee"/>
</enterprise-beans>
<assembly-descriptor>
<default-method-access>
<security-role-mapping impliesAll="true" name="&lt;default-ejb-
caller-role>"/>
</default-method-access>
</assembly-descriptor>
</orion-ejb-jar>


500 Internal Server Error
javax.servlet.jsp.JspException: NamingException: java:comp/env/
UpdateEmployee not found in practice17-webtier-webapp
at com.evermind[Oracle Containers for J2EE 10g
(10.1.3.1.1) ].ejb.taglib.UseHomeTag.doStartTag(UseHomeTag.java:80)
at _AddEmployees._jspService(_AddEmployees.java:61)
[/AddEmployees.jsp]
at com.orionserver[Oracle Containers for J2EE 10g
(10.1.3.1.1) ].http.OrionHttpJspPage.service(OrionHttpJspPage.java:59)
at oracle.jsp.runtimev2.JspPageTable.service(JspPageTable.java:462)
at oracle.jsp.runtimev2.JspServlet.internalService(JspServlet.java:
598)
at oracle.jsp.runtimev2.JspServlet.service(JspServlet.java:522)
at javax.servlet.http.HttpServlet.service(HttpServlet.java:856)
at com.evermind[Oracle Containers for J2EE 10g
(10.1.3.1.1) ].server.http.ServletRequestDispatcher.invoke(ServletRequestDispatcher.java:
712)
at com.evermind[Oracle Containers for J2EE 10g
(10.1.3.1.1) ].server.http.ServletRequestDispatcher.forwardInternal(ServletRequestDispatcher.java:
369)
at com.evermind[Oracle Containers for J2EE 10g
(10.1.3.1.1) ].server.http.HttpRequestHandler.doProcessRequest(HttpRequestHandler.java:
865)
at com.evermind[Oracle Containers for J2EE 10g
(10.1.3.1.1) ].server.http.HttpRequestHandler.processRequest(HttpRequestHandler.java:
447)
at com.evermind[Oracle Containers for J2EE 10g
(10.1.3.1.1) ].server.http.HttpRequestHandler.serveOneRequest(HttpRequestHandler.java:
215)
at com.evermind[Oracle Containers for J2EE 10g
(10.1.3.1.1) ].server.http.HttpRequestHandler.run(HttpRequestHandler.java:
117)
at com.evermind[Oracle Containers for J2EE 10g
(10.1.3.1.1) ].server.http.HttpRequestHandler.run(HttpRequestHandler.java:
110)
at oracle.oc4j.network.ServerSocketReadHandler
$SafeRunnable.run(ServerSocketReadHandler.java:260)
at
oracle.oc4j.network.ServerSocketAcceptHandler.procClientSocket(ServerSocketAcceptHandler.java:
239)
at oracle.oc4j.network.ServerSocketAcceptHandler.access
$700(ServerSocketAcceptHandler.java:34)
at oracle.oc4j.network.ServerSocketAcceptHandler
$AcceptHandlerHorse.run(ServerSocketAcceptHandler.java:880)
at com.evermind[Oracle Containers for J2EE 10g
(10.1.3.1.1) ].util.ReleasableResourcePooledExecutor
$MyWorker.run(ReleasableResourcePooledExecutor.java:303)
at java.lang.Thread.run(Thread.java:595)