Help needed with QueryPlan

Hi,
I have a query that runs pretty slow and tried to use explain to see
where the problem is.
Both tables have 2.1 and 2.8 million records.

In the Explain output I see that a Seq Scan is used on nval_price_hist
what I dont quite understand.
Could some one help me creating the correct indices?

SELECT ..........
FROM price_hist AS P, nval_price_hist AS N
WHERE P.price_id = N.price_id AND P.sec_code = 512084 AND P.eval_date =
'2004-10-15' ;

Hash Join  (cost=210.16..61370.19 rows=53 width=602)
   Hash Cond: ("outer".price_id = "inner".price_id)
   ->  Seq Scan on nval_price_hist n  (cost=0.00..50575.00 rows=2116900
width=65)
   ->  Hash  (cost=209.99..209.99 rows=69 width=537)
         ->  Index Scan using price_hist_idx1 on price_hist p
(cost=0.00..209.99 rows=69 width=537)
               Index Cond: ((eval_date = '2004-10-15'::date) AND
(sec_code = 512084))

Indices on nval_price_hist

    "nval_price_hist_pkey" primary key, btree (price_id, logic_id)
    "nval_price_hist_idx1" btree (sec_code, exch_code, sec_type,
nval_price_date, logic_id)
    "nval_price_hist_idx2" btree (nval_price_date, logic_id)
    "nval_price_hist_idx3" btree (price_id)
    "nval_price_hist_idx4" btree (sec_code, nval_price_date)

Thanks
Alex