Hi !!
the problem is that i can´t see the DOI of the PDF in my journal OJS 3.0.2, i dont know if the DOI that i can see is PDF’s DOI, because when you enter, you go to the page of the magazine.
If you are using Crossref DOIs then the DOI should point to the article landing page (=the abstract page) and not straight to the PDF file. Your landing page – Support Center
But if you have a DOI for the actual PDF file, how did you register it?