Help SQL*Net V2 and Pro*C

I'm having a problem using a Pro*C 2.2 program to connect to a remote database (Oracle 7.3.2) using SQL*Net V2. I can successfully connect to a local db using the following:

   EXEC SQL CONNECT :oracle_user IDENTIFIED BY :oracle_pword;

But when I try to connect to the remote db using the following:

   EXEC SQL DECLARE mydb DATABASE:
   EXEC SQL CONNECT :oracle_user IDENTIFIED BY :oracle_pword AT mydb USING :oracle_tns;

I get ora-12203 (TNS unable to connect to destination). However SQL*Net works OK so I'm assuming there's a problem with my connect string. BTW, all the host variables are declared as VARCHAR.

Oracle Tech Supp seems unable to resolve this problem. Anyone out there have any ideas?

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Name: Darrell Coons
E-Mail: darrell_coons_at_mc.xerox.com