starbuck7777 on "[Plugin: Contact Form 7] Date format seems invalid"

I added this tag to create a field date

<p>Data
[date data]</p>

but there is this problem

I tried to add the date "11.11.2013" in various formats "mm-dd-yy", "mm-dd-yyyy", "mm /dd/yy", "mm/dd/yyyy" but always appears this error "date format seems invalid."

same thing in the administrative part, if i try to insert the min date or max date the value not stored in the field

what is the exact format for the date?

is it possible change this input format in "dd/mm/yyyy" or "dd-mm-yyyy" format
thank you

I use CF7 3.4 and this is the link of the page :
http://www.digitalphotoarcevia.it/contatti/

http://wordpress.org/extend/plugins/contact-form-7/