cant get domain mapping to map domains

hi,

i have tried mapping domains using the domain mapping. Hosting is currently with hostgator. domain is parked. The information is saved in the database. What happens is if i do not add the nameserver or a record to the domain i want to map, then in my wordpress install it does redirect (to a go daddy blank page- where domain is from). But when i add the name server, the domain does not map, it only goes to the main website.

MY current website is ycreateawebsite.com
a domain i am mapping is fatstomachflat.com.
the subdirectory is ycreateawebsite.com/fv

I can provide you my cpanel details and my wordpress details as this is a test install. I have had the same problem with another install as well.

i have been trying to fix this for two weeks. any help would be appreciated