Multiple WP installations on addon domains

Hello,

I have a hosting account with namecheap where I can host multiple domains. I installed WP on one addon domain (www.besteugenedayspa.com), and it works fine.

I installed on a 2nd addon domain (www.besteugenerestaurant.com), and it works during setup, then after I log out and come back, the site is down. (404 site not found)

This has happened twice (I uninstalled/reinstalled after the first time).

I was wondering if there is something special I need to do in this case to get WP working on multiple domains.

Thanks for your help,
Jeremy