domain not being accepted - errors

when i go to add custom domain:
books.scottastle.com

domain verifies.

Thank I go to hit "OK"

and it says

"there is an error in changing your domain. try again"

no matter how many times I try - same error

support response turn around time is not conducive to the timeline I'm working on.
i need this domain up and operating - ASAP.
please directly FIX whatever is stopping the domain registration of
Books.ScottAstle.com for this site build.

-Scott

17hrs - no response from support.
still can connect to domain.
same error

Hello Scott,

Nicepage support is available on business days, from Monday to Friday.

Your domain name is pointing to Nicepage IP now, please publish your site with Nicepage again to check the connection and let us know.
In case of any error messages, take a screenshot and send it.
...................................................
Sincerely,
Anna.
Nicepage Support Team

Please subscribe to our YouTube channel: http://youtube.com/nicepage?sub_confirmation=1
Follow us on Facebook: http://facebook.com/nicepageapp

same error.
repeatedly.
all weekend.
nothing fixed.
see attached.

Do you guys only respond once a day?
I would like to get this error situation rectified promptly.
My website can't publish until this is resolved.

Hello Scott,

Please do not worry, our admins are checking the issue with the custom domain books.scottastle.com and we will let you know the result.
...................................................
Sincerely,
Anna.
Nicepage Support Team

Please subscribe to our YouTube channel: http://youtube.com/nicepage?sub_confirmation=1
Follow us on Facebook: http://facebook.com/nicepageapp