Postgres 9.2 - XML string functions ?

Hi

Please help, I have been asked why XML string functions do this, which is
why does the second statement below return no rows. No matter what is on
the select statement, they can select as many columns as they want but the
XML function breaks it as soon as it is added.

1) select
aud_id,act_typ,right(act_typ::text,1),fpp_cde,obo_aud_id,obo_aud_id||sku_cde
as "Key" from sku_tran join audit using (aud_id) join action_typ using
(act_typ) join branch using (br_cde) join sku using (sku_cde) where
obo_aud_id=5252005 and audit.fpp_cde between '201408' and '201412' and
(right(act_typ::text,1) = '5') and act_typ between 76000 and 76999;

aud_id | act_typ | right | fpp_cde | obo_aud_id | Key

2585912 | 76005 | 5 | 201408 | 5252005 | 525200510053486

(1 row)

2) select
aud_id,act_typ,right(act_typ::text,1),fpp_cde,obo_aud_id,(unnest(xpath('.//checksumBr/text()',
aud_xml::xml)))::text||obo_aud_id||sku_cde as "Key" from sku_tran join
audit using (aud_id) join action_typ using (act_typ) join branch using
(br_cde) join sku using (sku_cde) where obo_aud_id=5252005 and
audit.fpp_cde between '201408' and '201412' and (right(act_typ::text,1) =
'5') and act_typ between 76000 and 76999;

aud_id | act_typ | right | fpp_cde | obo_aud_id | Key

(0 rows)

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