plesk denies hostname

[dragoncorp]

im still basically in the install/setup process for plesk, and it keep's denieing my hostname. yes im using my computer name DRAGONCO-SERVER, it keeps popping up saying invalid field. also since i have to port forward behind a router my ip on the list is 192.168.1.100 for the shared ip's. do i select that? what am i doing wrong??