ORA-12154: TNS:could not resolve the connect identifier specified

Hello All,

I am confused as to why I am getting this error message. I am trying to
connect to two different Oracle instances within one program run. The
two Oracle instances are different in versions. inst1 is 9.2 while
inst2 is 10.2. I am able to connect to the first instance without
problems, but the instance yields "ORA-12154" error. However, when I
reverse the connection order by connecting the inst2 with 10.2 version
first, then connecting to the inst1 with 9.2 version, there is no error.
I hope someone can shed some lite. Here is the code:

#!/usr/bin/perl

use DBI;

$ENV{'ORACLE_HOME'} = "/opt/app/oracle/product/9.2";
$ENV{'PATH'} =
"/opt/app/oracle/product/9.2/bin:/usr/ccs/bin:/opt/studio9/SUNWspro/bin:
/opt/app/oracle/product/10.2/bin:/opt/CA/Shar
edComponents/dmscript/bin:/usr/bin:/usr/bin:/bin:/usr/sbin:/sbin:/usr/lo
cal/bin:/opt/app/oracle/product/8.1.7.4/bin:/usr/local/bin:/
usr/local/apps/common/devl/bin:/usr/lbin:/usr/ccs/bin:/usr/xpg4/bin:/opt
/pkware:/opt/RICHPse/bin:/opt/RICHPse/examples:/opt/sas82:/o
pt/sas82/sasexe:/opt/Navisphere/bin:/opt/fileport/bin:/opt/syncsort/bin:
/usr/bin:/usr/openwin/bin:/opt/SUNWspro/bin:/opt/mfcobol/cob
ol/bin:/opt/starsql/bin:/opt/uni/bin:/opt/uni/scripts:/etc:/opt/emc/EMCp
ower/bin/sparcv9:/etc/emc/bin:/usr/local/nz/bin/:.";

my $dbh_inst1 = DBI->connect("dbi:Oracle:inst1", "schema", "password", {
RaiseError => 1, PrintError => 1});

$ENV{'ORACLE_HOME'} = "/opt/app/oracle/product/10.2";
$ENV{'PATH'} =
"/opt/app/oracle/product/10.2/bin:/opt/app/oracle/product/9.2/bin:/usr/c
cs/bin:/opt/studio9/SUNWspro/bin:/opt/CA/Shar
edComponents/dmscript/bin:/usr/bin:/usr/bin:/bin:/usr/sbin:/sbin:/usr/lo
cal/bin:/opt/app/oracle/product/8.1.7.4/bin:/usr/local/bin:/
usr/local/apps/common/devl/bin:/usr/lbin:/usr/ccs/bin:/usr/xpg4/bin:/opt
/pkware:/opt/RICHPse/bin:/opt/RICHPse/examples:/opt/sas82:/o
pt/sas82/sasexe:/opt/Navisphere/bin:/opt/fileport/bin:/opt/syncsort/bin:
/usr/bin:/usr/openwin/bin:/opt/SUNWspro/bin:/opt/mfcobol/cob
ol/bin:/opt/starsql/bin:/opt/uni/bin:/opt/uni/scripts:/etc:/opt/emc/EMCp
ower/bin/sparcv9:/etc/emc/bin:/usr/local/nz/bin/:.";

my $dbh_inst2 = DBI->connect("dbi:Oracle:inst2", "schema", "password", {
RaiseError => 1, PrintError => 1});

$dbh_inst1->disconnect();
$dbh_inst2->disconnect();

exit;

Here is the error message:

DBI connect('inst2','schema',...) failed: ORA-12154: TNS:could not
resolve the connect identifier specified (DBD ERROR: OCIServerAttach)

Thanks.

Peter