Your database is not configured for session failover. Your tnsnames.ora file contains the following details:
test.us.oracle.com= (DESCRIPTION=
(ADDRESS_LIST= (LOAD_BALANCE=off)
(FAILOVER=ON)
(ADDRESS= (PROTOCOL=tcp)(HOST=test1-server)(PORT=1521))
(ADDRESS= (PROTOCOL=tcp)(HOST=test2-server)(PORT=1521)))
(CONNECT_DATA= (SERVICE_NAME=test.us.oracle.com)))
Which feature is enabled in this case?()