Refer http://contactform7.com/date-field/ - DD-MM-YYYY format is not supported.
The new CF7 date tag is a HTML5 date input type which currently has only limited cross-browser support. See http://www.wufoo.com/html5/types/4-date.html for the low down on this new HTML5 form element.
As per the Forum Welcome, please post your own topic. Posting in an existing topic prevents us from being able to track issues by topic. Added to which, your problem - despite any similarity in symptoms - is likely to be completely different.