Index not recognized

Hello.

Why is it that my index for text[] data type is not recognized by the
Planner?

I did these steps:

1. create function textarr(text[]) returns text language sql as 'select
$1[1]' strict immutable
2. create index org_idx on EmpData (textarr(org));

3. vacuum full
4. explain analyze select name from EmpData where org *= 'math';

Result:
=========
Seq Scan on EmpData (cost=0.00..3193.20 rows=102 width=488)
(actual time=3.71.35..371.35 rows=0 loops=1)

Filter: (org[0]='math'::text)

Total runtime: 371.47 msec
(3 rows)

==========

I have 20,496 records. My postgres version is 7.3.

Any help is greatly appreciated.

Thank you..

Ace