Have you created a reseller in HC panel ?
Secondly if you are not importing user with domain then did you created a webadmin (End User ) to import that site ?
Before importing test the control panel and make sure you can create a test user and website in HC.
Here are some good info which helps in starting work in the HC panel
How to start work in HC panel
1= Enable 3rd party installed tools in HC panel like Dns, Ftp, Mail server, Scripting etc, Go to “HCadmin :: Server Manager :: Global Setting ” (Enable only those one which are installed )
See Flash tutorial : http://hostingcontroller.com/english/support/HC8Manuals/videos/GlobalSettings/GlobalSettings2.htm
Then Add Server in the cluster, which usually we do with installation, but if it is not then you can do it from HCadmin :: Server manager :: Add server
See Flash Tutorial : http://hostingcontroller.com/english/support/HC8Manuals/videos/AddServer/AddServer.htm
2= Configure path of different applications in HC panel like ‘ WebSite root folder, Dns, Mail, databases Server from “ HCadmin :: Server Manager :: Edit Server “.
3= Update User Profile See flash tutorial http://hostingcontroller.com/english/support/HC8Manuals/videos/UpdatePersonalProfile/UpdatePersonalProfile.htm
4= Create reseller into HC8 panel who can only create websites/webadmin from ‘ User Manager :: Add User “
5= Login in HC as reseller and create package plan which he will offer to their end user from ‘ Hosting Plan :: Add Plan “.
6= Create website from reseller level interface path “ WebSite :: Add WebSite “
7= All website related applications are located in menu “ TOOL “