Remeber when you did your unit test on the same machine (or did you?), you set the (Hashtable) env variables as follows:

		env = new Hashtable();
		env.put(Context.INITIAL_CONTEXT_FACTORY, "org.jnp.interfaces.NamingContextFactory");
		env.put(Context.PROVIDER_URL, "localhost:1099");
		env.put("java.naming.factory.url.pkgs", "org.jboss.naming:org.jnp.interfaces");

(The above is for JBoss, since you do not mention a container. Other containers would not deviate too far from this)

Looking at PROVIDER_URL, the rest (as they say) is "elementary"

Cheers

-raj