Problebs with index in 7.0

Hi all,
I made an update (pg_dump) from 6.5 to 7.0 (i686-pc-linux-gnu, compiled
by gcc egcs-2.91.66),

I created an index on column gmkg_tl by doing:
create index ix_flurst_gmkg_tl_ix on flurstueck using btree (gmkg_tl
bpchar_ops);

gmkg_tl is char(16).

When I do a
select * from flurstueck where gmkg_tl = 'kaBV00110x9W06Zq';

in version 6.5 the query plan is:
Aggregate  (cost=124.82 rows=1217 width=12)
  ->  Index Scan using ix_flurst_gmkg_tl on flurstueck  (cost=124.82
rows=1217 width=12)

this is ok but when I do the same thing in version 7.0 the query plan
is:
NOTICE:  QUERY PLAN:

Seq Scan on flurstueck  (cost=0.00..4784.31 rows=2445 width=16)

yes, I did a vacuum/vacuum analyze

Some ideas???
Thanks,
Peter
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