Merge tags not working properly

When I customise the registration confirmation, none of the merge tags shows the data of the user I have created in the automated email I receive in the registered email.

I create the users manually via the admin panel for adding new users, and I fill in all the data related to the merge tags, because we do not use a registration form for the users to fill in. Could this be the problem? If so, how to solve it?

Thank you!