"java.lang.NoSuchFieldError: org/apache/log4j/Level.TRACELorg/apache/log4j/Level" using EAP 6 client library

Issue

We are calling EJBs on JBoss remotely, and get this error although we have log4j in the classpath.

javax.naming.NamingException: Failed to create remoting connection [Root exception is java.lang.NoSuchFieldError: org/apache/log4j/Level.TRACELorg/apache/log4j/Level;]
 at org.jboss.naming.remote.client.ClientUtil.namingException(ClientUtil.java:51)
 at org.jboss.naming.remote.client.InitialContextFactory.getInitialContext(InitialContextFactory.java:152)
 at javax.naming.spi.NamingManager.getInitialContext(NamingManager.java:667)
 at javax.naming.InitialContext.getDefaultInitCtx(InitialContext.java:288)
 at javax.naming.InitialContext.init(InitialContext.java:223)
 at javax.naming.InitialContext.<init>(InitialContext.java:197)
 ...