The username which you have entered belongs to a different deployment/region" error message

The username which you have entered belongs to a different deployment/region" error message

I am trying to create a email for my business (3dgeneration.com.ua)
when  i tried to signup with the above domain i am getting
 " The username which you have entered belongs to a different deployment/region" error message.

Can you please help us to complete the signup




Thanks
Rob Thibault