ORA-12154 error when using Oracle Instant Client

Question

I am getting this error trying to do a test connection on an ODBC DSN with the Oracle Instant client setup on Windows 7 32 bit. I have it working on another machine with Vista 32 bit.

Info:
1. Dir Structure is: c:\oracle\instantclient_11_2. Basic client and instant client files in the instantclient_11_2 directory, just like on the working machine.
2. c:\oracle and c:\oracle\instantclient_11_2 in system path
3. Added TNS_ADMIN to system path and pointed in to c:\oracle
4. tnsnames.ora is copied from the working machine and in c:\oracle
5. sqlnet.ora is in c:\oracle. Working copy just had "TCP.CONNECT_TIMEOUT=5" as an entry but I tried adding: NAMES.DIRECTORY_PATH= (LDAP, TNSNAMES, HOSTNAME) when it wasn't working
6. I can telnet to the oracle server and the 1521 port (defined in tnsnames.ora).

Anything else to check?

Answer 1

If yout tnsnames.ora is as you said in a comment, then you're using the wrong value in your DSN. You need to use the TNS alias in the DSN, which is ABCDM. You can't refer to the service name directly, unless you happen to have used that as the alias as well.

Answer 2

We have found that error to be returned when the application calling it is installed in the Program Files (x86) directory. Reinstalling the program outside that folder will clear the error. Not sure why the Oracle Instant Client won't play nice with programs installed there.