I am getting "javax.naming.NameNotFoundException: ProxyFactory not bound" when looking up one EJB from another EJB in JBoss.

Issue

While using JBoss EAP 5. If we want to implement the following scenario:
FirstEJB running on Application Server A on Machine1.
SeconEJB running on Application Server B on Machine2.

Invoke on both the EJB's independantly are successful.

but while calling FirstEJB in SecondEJB, produces the following error:

Caused by: javax.naming.NameNotFoundException: ProxyFactory not bound
    at org.jnp.server.NamingServer.getBinding(NamingServer.java:771)
    at org.jnp.server.NamingServer.getBinding(NamingServer.java:779)
    at org.jnp.server.NamingServer.getObject(NamingServer.java:785)
    at org.jnp.server.NamingServer.lookup(NamingServer.java:396