URL shortener links not sticking

We did some research and it seems most competitors have URL shortener links (bit.ly or similar) indexed as backlinks. We tried creating these high DA, easy-to-add shortener links but they don't get indexed and don't show up in backlinks. What is the issue with that kind of links? Google is not indexing them anymore?

I guess I posted in the wrong thread... could somebody please move this to Black hat SEO ?

Build backlinks to your shortened urls. Like a forum post, profile or blog commenting. It can do the indexing job.