I'm working on a php project.. And I started building the admin login system and have already finished it and it works properly on my machine (local server) where I'm developing the project.. But when I moved it to a (web server) it didn't work properly as it was working on (local server).

the problem that showed up is that when the admin get authentication to log in to the admin area, once he clicks any link in the page or even he reloads the page that page disappear and the login page appear again which mean the admin forced to log out even he didn't.