At the moment it seems that I solved.
I realized that if the field "cb_tipo_registrazione" = "Persona" when I confirm the registration is the error of the field "cb_tipo_organizzazione"
Error: "The field is mandatory cb_tipo_organizzazione"
If, instead, "cb_tipo_registrazione" = "Organizzazione" recording it works.
I discovered that the problem is a Conditional Tab that contains the field captcha mandatory and is called only if "cb_tipo_registrazione" = "Organizzazione".
I disabled the Tab and now it works.
CB Conditional does not work well because it returns the error on a different field of the cause and the tab conditional seems, at this point, that does not work well.
I hope I can be of help to understand and I explained myself.