I am using UltraVNC on my Windows machines and the good thing is that the application is still running after one user logs out. Then another user can go in and login.

I am trying the same solution with OSXvnc on a Mac. The VNC works as long as someone is logged in but when that person logs out the VNC is no longer active.

I need a VNC client to stay active even when the Mac is at the login screen, where all users are listed. How can I solve that?