You need to specify the column names in your view definition, INFORMIX won't implicitly assign column names from tables to the column names in your view so use something like this:
CREATE VIEW tkt_chrg (tr_dt, src_acct, descr, prod_descr, buysell, shares, unit_price, invested, recv, clearing, net) AS
SELECT a.traddate, a.source_acct, a.description, b.proddesc, a.buysell, a.shares, a.priceper,
a.invested, a.receivable, a.clearing, sum (a.receivable-a.clearing) as net
FROM
open_blot a, producttype b
WHERE a.prodtype = b.productype AND
a.prodtype in ('11','12') AND
a.traddate > = '01/01/2009'
group by 1,2,3,4,5,6,7,8,9,10