Perl Net::LDAP doesn't provide uidnumber under Sun Solaris

Dear experts,

I am using the Net::LDAP module on a Sun Solaris 64-bit Sparc machiune under perl version 5.13 to try to look up a numeric user ID and obtain the corresponding character login ID.  Everything works fine if I do the search based on the character login ID, but not if I do it based on the numeric UID.  I'm able to bind successfully, then use the instruction
$msg = $ldap -> search
    (
        base => "ou=People, dc=Enterprise, dc=mycompany, dc=com",
        filter => "uid=$parm_login_ID"
    );

But the attribute uidnumber does not appear in the list of values returned for a matching character login ID value.  I get no hits when I change the above instruction to "uidnumber=$parm_numeric_UID".  According to on-line reference materials, the attribute uidnumber is supposed to be part of the same database as is uid, viz. People, but it doesn't show up anywhere.  Is there anything wrong with my program, or did my company configure its local ldap database such that uidnumber is simply not an available attribute?

Thank you!