Erro ao usar JSF + JBoss 4.0.5

Olá,

Fiz uma pequena aplicação que roda bem no Tomcat 6, porém ao fazer deploy no JBoss 4.0.5 tenho o seguinte erro:

javax.servlet.ServletException: Servlet.init() for servlet Faces Servlet threw exception

org.jboss.web.tomcat.security.SecurityAssociationValve.invoke(SecurityAssociationValve.java:175)

org.jboss.web.tomcat.security.JaccContextValve.invoke(JaccContextValve.java:74)

org.apache.catalina.valves.ErrorReportValve.invoke(ErrorReportValve.java:105)

org.jboss.web.tomcat.tc5.jca.CachedConnectionValve.invoke(CachedConnectionValve.java:156)

org.apache.catalina.connector.CoyoteAdapter.service(CoyoteAdapter.java:148)

org.apache.coyote.http11.Http11Processor.process(Http11Processor.java:869)

org.apache.coyote.http11.Http11BaseProtocol$Http11ConnectionHandler.processConnection(Http11BaseProtocol.java:664)

org.apache.tomcat.util.net.PoolTcpEndpoint.processSocket(PoolTcpEndpoint.java:527)

org.apache.tomcat.util.net.MasterSlaveWorkerThread.run(MasterSlaveWorkerThread.java:112)

java.lang.Thread.run(Thread.java:619)

java.lang.IllegalStateException: Application was not properly initialized at startup, could not find Factory: javax.faces.context.FacesContextFactory

javax.faces.FactoryFinder.getFactory(FactoryFinder.java:256)

javax.faces.webapp.FacesServlet.init(FacesServlet.java:142)

org.jboss.web.tomcat.security.SecurityAssociationValve.invoke(SecurityAssociationValve.java:175)

…