varchar value comparisons not working?

Hello,

I'm doing a quick comparison between a couple tables, trying to cleanup
some inconsistencies, and what should be a simple check between 2 tables
doesn't seem to be working. psql is 8.3.7 and server is 8.2.13.

I run the following:

select sfd.lid as sflid,sd.lid as slid,sfd.serial from sfd,shawns_data
sd where sfd.serial = sd.serial_number order by sfd.lid;

the lid columns in both tables should be identical, but as you see in
this sample, they do differ:

sflid | slid | serial
-------+-------+----------
14056 | 14056 | 9614583
14057 | | 9614984
14058 | 14058 | 9614737
14059 | 14059 | 9614579
14060 | | 9614827
14061 | 14061 | 9614726
14062 | 14062 | 9614966
14063 | 14063 | 9615079

So running this query:

select count(*) from sfd,shawns_data sd where sfd.serial = sd.serial_number and sfd.lid != sd.lid;

I should show some rows that do not match, at least 2 (there are more than shown).

But instead I get this:

count
-------
0
(1 row)

What am I doing wrong?

--
Sincerely,

Shawn Tayler
Radio Network Administrator
Washoe County Regional Communications System
Telecommunications Division
Technology Services Department
County of Washoe
State of Nevada
Ofc (775)858-5952
Cell (775)771-4241
FAX (775)858-5960