Can't add my dads account on xbox no error message

I dont have any other accounts to try to add they were already on. I did a hard reset it didnt help

Have you tried adding other members of your family to the console to see if it works when adding them?

Try doing a hard reset of the console by holding down the power button for ten seconds before releasing and oressing the power button again.

Are you trying to add him as a friend or are you trying to add his account to your xbox?

But I can't I made the account on my xbox live account on my Dads email

Are you getting any specific error messages?

Here is a link that may help:
Xbox Can't Send Messages

If it is just happening on the xbox, and not through the website, it might be worth trying to remove your profile and re-add it: Add
or Remove Profile

Hopefully this helps