pg_dump: aborting because of version mismatch

>>I am keep getting error of mismatch of pg_dump version. how should one
dealing with different version of pg_dump normally?

C:\Program Files\pgAdmin III\1.8\pg_dump.exe -h 192.168.222.129 -p 5433 -U
postgres -F c -b -v -f "C:\Documents and
Settings\steven\Desktop\template.backup" template_postgis
pg_dump: server version: 8.3.9; pg_dump version: 8.3.0
pg_dump: aborting because of version mismatch (Use the -i option to proceed
anyway.)
pg_dump: *** aborted because of error

Process returned exit code 1.

>>If I use the '-i' option it still give the following error

[postgres(at)localhost ~]$ pg_dump -h 172.16.1.246 -p 5432 -U postgres -Fc -i
postgres > postgres
Password:
pg_dump.bin: server version: 8.4.0; pg_dump.bin version: 8.3.9
pg_dump.bin: proceeding despite version mismatch
pg_dump.bin: SQL command failed
pg_dump.bin: Error message from server: ERROR: column "reltriggers" does
not exist
LINE 1: ...oles WHERE oid = relowner) as rolname, relchecks, reltrigger...
^
pg_dump.bin: The command was: SELECT c.tableoid, c.oid, relname, relacl,
relkind, relnamespace, (SELECT rolname FROM pg_catalog.pg_roles WHERE oid =
relowner) as rolname, relchecks, reltriggers, relhasindex, relhasrules,
relhasoids, d.refobjid as owning_tab, d.refobjsubid as owning_col, (SELECT
spcname FROM pg_tablespace t WHERE t.oid = c.reltablespace) AS
reltablespace, array_to_string(c.reloptions, ', ') as reloptions from
pg_class c left join pg_depend d on (c.relkind = 'S' and d.classid =
c.tableoid and d.objid = c.oid and d.objsubid = 0 and d.refclassid =
c.tableoid and d.deptype = 'a') where relkind in ('r', 'S', 'v', 'c') order
by c.oid