PHP4, PWS, Oracle, cannot connect, HELP!

I am running Winnt Workstation 4.0, PWS 4.0, PHP4, and Oracle 8.1.5 (on a
different box).
I also have PHP3 installed.

When I attempt to connect to an Oracle database from PHP3 it works fine.
When I attempt to connect to the same database with PHP4, with the exact same
code I get this error:
Warning: Oracle: Connection Failed: ORA-12154: TNS:could not resolve service
name in
c:\inetpub\wwwroot\test\oratest.php4 on line 2

Here is my test code:
<?
$conn = Ora_Logon("msds@tst3.world", "password") or die;
$curs = ora_open($conn);
ora_commitoff($conn);
$query = sprintf("select * from msds");
ora_parse($curs, $query);
ora_exec($curs);
$ncols = ora_numcols($curs);
while (ora_fetch($curs))
{
for ($i=0; $i<$ncols; $i++)
{
printf("%s = %s", ora_columnname($curs,$i), ora_getcolumn($curs,$i));
printf("<br>");
} }
ora_close($curs);
ora_logoff($conn);
?>

I can connect to the database and execute the SQL from SQL-Plus. I *know* that
Oracle name resolution works.

Please help, if I can get this working then I can use PHP instead of ASP. I need
to use PHP4 for session
support. I don't want to use PHPLIB because I will eventually move this code to
a Solaris box and I want to use
'pure' PHP4 if at all possible.
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