Connections not getting failed over to stand-by DB

Hi,

I'm trying to configure a load balancer infront the oracle databases. There are two DBs: one acts as the live and the other is the stand-by. Both the databases are configured under the same pool. The problem is that even if we for the live database offline from the loadbalancer, and make the standby database active, the connections are not getting failed over to the database that was just brough into rotation. From the client, I'm able observe established connections to the database that is out of rotation. Only when we restart the client side processes, the connections gets failed over.What could be possibly causing this behaviour?

Thanks,

Prashanna B