Gitlab pages not working, what could be the problem?

Question

GitLab

Can't set up gitlab pages.

I add the .gitlab-ci.yml file and paste these settings into it (added below).

But nothing happens, it does not connect, there is no check mark. And on another, old project, everything works OK. Tell me what could be the problem? Thanks for answer

setting in .gitlab-ci.yml file
pages:
stage: deploy
script:
- mkdir .public
- cp -r * .public
- mv .public public
artifacts:
paths:
- public
only:
- master