DBD::Oracle 'make test' fails - ORA-24327: need explicit attach before authenticating a user

Hi Everybody,
 
I am trying to install DBD::Oracle 1.27 on Red Hat Enterprise Linux Server release 5.5 (Tikanga), Linux 2.6.18-194.17.1.el5 x86_64 x86_64 x86_64 GNU/Linux. I have already deployed the latest Oracle InstantClient and can connect to the Oracle server (running on a different box) via sqlplus. Since I'm not allowed to log on as 'root', I am installing everything in my home directory. I set the ORACLE_HOME, TNS_ADMIN, ORACLE_SID, ORACLE_USERID, LD_LIBRARY_PATH, C_INCLUDE_PATH and PERL5LIB environment variables to include everything needed for the Perl module to be happy, as well as creating tnsnames.ora and sqlnet.ora files. I can 'make' DBD::Oracle okay, but "make test" fails with the following error:
 
PERL_DL_NONLAZY=1 /usr/bin/perl "-MExtUtils::Command::MM" "-e" "test_harness(0, 'blib/lib', 'blib/arch')" t/*.t
t/01base................# Test loading DBI, DBD::Oracle and version
t/01base................ok
t/10general.............DBI connect('','user/password',...) failed: ORA-24327: need explicit attach before authenticating a user (DBD ERROR: OCISessionBegin) at t/10general.t line 22
FAILED--Further testing stopped: Unable to connect to Oracle (ORA-24327: need explicit attach before authenticating a user (DBD ERROR: OCISessionBegin))
make: *** [test_dynamic] Error 9
 
Of course, the real username and password are sent to the Oracle server, the same that allow me to connect to it from sqlplus. I wonder what could cause that error? I have done some search on the Internet, but was unable to find any definitive solution.
 
Thanks in advance,
 
Alexander Saip