Postgresql currval error when submit newsLetter

When I tried to submit a newsletter, I have the following error :

pdoexception : SQLSTATE[55000]: Object not in prerequisite state: 7 ERROR: currval of sequence "simplenews_mail_spool" is not yet defined in this session: INSERT INTO simplenews_mail_spool(mail, snid, tid, nid, status, timestamp) SELECT s.mail, AS mail, s.snid AS snid ....................... Array() dans simplenews_add_node_to_spool()(ligne 36 dans ...../sites/modules/simplenews/includes/simplenews.mail.inc

Drupal 7, Simplenews 7.x-1.1 and then tried with simplenews 7.x-2.x

I have made the following modification, no more error, but for the moment I don't recieve the newsletter.

Here are the modification I have made :

In ligne 36
replace
db_insert('simplenews_mail_spool')

by
 db_insert('simplenews_mail_spool' , array('return' => Database::RETURN_NULL))

I have took other issue patch as example, but I am not sure of what this really do.

Thanks for all the job you do for this module.