This is a new Zen Cart install on a new host. I can get to the Zen cart itself but cannot display the admin login window. Attempts to display the login result in either a blank page or the prior page (zen cart) remaining on screen. The cart was installed via Fantastico/cPanel.
Then upload the files to your site in the same format as your current site to make sure that all files are current, up to date and that there are no file corruptions or missing files ...