drupal 7: how to add a field that displays a message when user is not logged in?
You can try the following 2 modules: Field Permissions and Markup.


Define the field.
Directly behind, define the markup field that shows the message to log in.
Use field permissions to allow access to the target field for authenticated users only.
Use field permissions to allow access to the markup field for anonymous users only.


That workaround should solve you issue.