Load Balancing issue across the Cluster EJB calls in Weblogic

Our Application has 2 Clusters running in Weblogic 12 C.

Each Cluster 4 Managed Servers. Cluster B is making EJB Call to Cluster A through Foreign JNDI . In Cluster A EJB Calls are not distributing across the managed server ? This results in overload of One Server in Cluster A. We are using round robin load balancing in Cluster Configuration.

Can you tell me any other configuration we can make in our Weblogic to make ejb calls get load balanced ?

Regards, Sakumar