infopath – Sharepoint 2013 – Conditional validation on the multiple choice search column

Scenario:
Sharepoint form created in Infopath with several views. A multiple-choice search column must be "Can not be empty" for only one of the views.
I've removed the ribbon backup button and added mine, and put some rules in it to disable it if the values ​​are not entered correctly. This works for all validation conditions, except for this multiple-choice search field, where the field is always calculated with a = non-empty value, so the record button is not never disabled.

So, how do I configure conditional validation on a multiple-choice search field?