What's going on here?

I can't seem to change any rows in this table. Are there locks somewhere
that I can look at or fix

ebox=# select version();
                           version
-------------------------------------------------------------
 PostgreSQL 7.0.3 on i686-pc-linux-gnu, compiled by gcc 2.96
(1 row)

ebox=# select eitemcode,itemavail from inventory where itemavail = 1
limit 1;
 eitemcode | itemavail
-----------+-----------
   6100122 |         1
(1 row)

ebox=# update inventory set itemavail=0 where eitemcode=6100122;
UPDATE 0

Thanks in advance,

Dave