JBoss: WAR file in EAR can't find JAR library on classpath

I am having a problem deploying an ear with bundled wars, jars, and configuration files (.properties files) on JBoss 4.3-eap. Here is my ear structure:

+app.ear   
  +lib  
    *.jar libraries that the war's use  
    +classes  
      *.properties and other configuration files 
  +META-INF  
    application.xml  
    jbos-app.xml  
  app.war  
  app2.war  
  appn.war  

I have the following in my jboss-app.xml :

<jboss-app>
  <jmx-name>app.startup.JbossStartUpServer:service=JbossStartUpService</jmx-name>
</jboss-app>    

My application.xml looks like this:

<application id="app_id">
  <display-name>App>/display-name>
  <description>TheApp>/description>
<!--  
  <module  id="core">
    <java>lib/core.jar</java>
  </module>

  <module id="tag">
    <java>lib/tag.jar</java>
  </module>
-->  
  <module id="app">
    <web>
      <web-uri>app.war</web-uri>
      <context-root>/</context-root>
    </web>
  </module> 

  <module id="app2">
    <web>
      <web-uri>app2.war</web-uri>
      <context-root>/app2</context-root>
    </web>
  </module> 

  <module id="appn">
    <web>
      <web-uri>appn.war</web-uri>
      <context-root>/appn</context-root>
    </web>
  </module>

  <security-role id="secRole">
    <description>users</description>
    <role-name id="appRoleName">users</role-name>
  </security-role>

  <library-directory>lib</library-directory>

</application>

Basically, upon deploying the ear, I run into an issue where one of my wars can't find a class in the core.jar file (java.lang.NoClassDefFoundError). I think this is due to