Trigger function cannot reference field name with capital letter

Hello PGSQL users,

I have a field called postTimestamp.
The trigger function could not reference it.
When I change my field to post_timestamp. I can reference it from the tigger function.
Version is 9.3.5. Any comment?

< 2014-08-14 00:23:32.717 HKT >ERROR:  post "new" has no field "posttimestamp"
< 2014-08-14 00:23:32.717 HKT >CONTEXT:  SQL statement "SELECT * from tbl1
        where NEW.posttimestamp > "2014-01-01 00:00:00" )"
        PL/pgSQL function test_trigger() line 9 at assignment
< 2014-08-14 00:23:32.717 HKT >STATEMENT:  INSERT INTO public.tbl1("vendor", url, "postTimestamp", product, "type", "itemID") VALUES ('vendor1'::text, 'http://example.org'::text, '2014-01-01 01:01:01'::timestamp without time zone, 'product1'::text, 'food'::text, '1'::bigint)
< 2014-08-14 00:32:39.708 HKT >ERROR:  syntax error at or near "SELECT" at character 314

Thanks and regards,
Patrick