ALTER TABLE sample SET TABLESPACE

Hello,  I speak little English language but try to understand me.

I am running   "PostgreSQL 7.4.1 on i686-pc-linux-gnu, compiled by GCC 
gcc (GCC) 3.3.2 (Mandrake Linux 10.0 3.3.2-6mdk)"  on a remote server
and running pgadminiii 1.8.0 RC1 on windows xp (ES)

When such change a "comment" on a table with pgadmin,  the application 
also try running:

ALTER TABLE sample SET TABLESPACE ;
COMMENT ON TABLE sample  IS 'sample table';

but SET TABLESPACE is not valid in 7.4.    I did not have this problem 
with 1.8.0 Beta 2  (only executed COMMENT ON TABLE sample  IS 'sample 
table';)

It is possible to resolve this? Or is that no longer supports old 
versions of  postgresql.?

Thank you.                              Ariel Giomi. ( Argentina)