Oracle problem

[Bart Kelsey]

I'm having some trouble with DBD::Oracle...
When I execute this code:
***
   $sth = $dbh->prepare("select * from abbrev where type = ?");
   $sth->execute("PAYMENT");
   while((@row) = $sth->fetchrow_array) {
     print(join(", ", @row), "\n");
   }
   $sth->finish;
***
... no rows are returned.  However, when I execute this code here:
***
   $sth = $dbh->prepare("select * from abbrev where type = 'PAYMENT'");
   $sth->execute();
   while((@row) = $sth->fetchrow_array) {
     print(join(", ", @row), "\n");
   }
   $sth->finish;
***
... it correctly returns a row.  Does anyone know what the problem might 
be?  I'm running DBD::Oracle 1.16 on Redhat Enterprise Linux 3, 
accessing Oracle 9.2.0.5.0.

Thanks,
Bart