OCI driver fails to resolve service name

I am using Oracle 9i OCI drivers to connect a java app to an oracle DB. The app is running on Weblogic8.1

The issue is this: When I deploy the application, the connections open just fine to Oracle 9i, using the oci drivers. But eventually they fail, and I get these TNS:could not resolve service name errors.
Initially, in the WebLogic start scripts, I am setting three variables for oci to work: ORACLE_HOME, LD_LIBRARY_PATH, and PATH.
I know these are all set correctly because I can connect through the app server to the database for the initial few days. Then for some reason out of the blue, I get the errors from WebLogic attached below:

#### <> <> #### <> #### <> java.sql.SQLException: ORA-12154: TNS:could not resolve service name

Has anyone else had this issue, or have any idea how to pursue this issue?
Help appreciated.

look at your tnsnames.ora file to see what is your tns alias you are trying to connect to.

Also Try "tnsping servicename" your alias to see if it's getting there.
You may need to provide the full alias name eg db.world or may be your host name doesn't get resolved .

Eugene Roytman
OCP DBA