How to add another site in wordpress multisite

Hi guys, I've read a ton of stuff about setting up a new site in multisite, which I think i have followed to a tee, but I have just tried to set another one up (I have 3 previous sites and they worked fine) but the last one I tried to set up just hasn't appeared on my network at all. How do i start to find out whats not happening correctly?
Appreciate your help with this.
I use cpanel hostgator as my hosting service and management system.
Dave