I have looked through the postings but cannot get a handle on this.  I
have connected to many Oracle databases in many environments using
JDBC but there is one that I cannot connect to.  I have the Oracle
client tools installed and I can connect using SQL*Plus using the Host
String PRODLAW.

The tnsnames.ora entry looks like this;
PRODLAW =
 (DESCRIPTION =
   (ADDRESS_LIST =
     (ADDRESS = (PROTOCOL = TCP)(HOST = db4.netaspx.com)(PORT =
1521))
     (ADDRESS = (PROTOCOL = TCP)(HOST = db5.netaspx.com)(PORT =
1521))
     (LOAD_BALANCE = yes)
   )
   (CONNECT_DATA =
     (SERVICE_NAME = c0ujP0.oracle.netaspx.com)
     (FAILOVER_MODE =
       (TYPE = SELECT)
       (METHOD = BASIC)
     )
   )
 )

The sqlnet.ora looks like this

# sqlnet.ora Network Configuration File: D:\Oracle\product
\10.1.0\Client_1\network\admin\sqlnet.ora
# Generated by Oracle configuration tools.

SQLNET.AUTHENTICATION_SERVICES= (NTS)

NAMES.DIRECTORY_PATH= (TNSNAMES, EZCONNECT)

The message I am getting looks like this

Driver: oracle.jdbc.driver.OracleDriver
Connecting to jdbc:oracle:thin:@db5.netaspx.com:1521:c0ujP0...
Driver registered: oracle.jdbc.driver.OracleDriver
Io exception: Connection refused(DESCRIPTION=(TMP=)(VSNNUM=169869824)
(ERR=12505)(ERROR_STACK=(ERROR=(CODE=12505)(EMFI=4))))

I CAN successfully connect to another instance defined in the same way
in the same environment.  Only this one particular dadtabase
connection fails.

Any ideas would be very much appreciated.