According to the JCA spec, AdminObjects are only guaranteed to be bound in JNDI by the JCA provider if javax.resource.Referenceable is implemented. See 22.214.171.124 "Administered Objects". A JMS provider is free to provide AdminObjects that implement only javax.naming.Referenceable in an otherwise unmanaged environment, but a resource adapter must allow the application server/jca container to use its own ObjectFactory and call setReference() on the admin objects that need to be looked up. See 20.6 JNDI Configuration and Lookup.
This is a problem for users using an application server such as the current release of AS7 which will not bind AdminObjects otherwise.