Pluggin crossref doi - ojs

Hello I want to assign the doi for the Magazine.
My boss has given me the suffix to put the volume, the file number, the type of file (article, interview, miscellaneous).
I had placed the following doi for the
a) Volume 1 Number 1 Article 1 = nw.1-1.1.01
b) Volume 1 Number 1 Article 2 = nw.1-1.1.02

but they don’t work.
description:
nw is the abbreviation of the magazine name
1-1 means volume 1 number 1
1 means the file type is an article
01 means it is item number 1

A) works, but b) does not.
What can I do to fix it?
http://www.revistas.espol.edu.ec/index.php/nawi/issue/view/17