minlength doesn't work

I have this field
[text* piva 11/ minlength:11]</p>
which should have at least 11 characters

this is the code output
<input type=”text” name=”piva” value=”asdf” size=”11″ class=”wpcf7-form-control wpcf7-text wpcf7-validates-as-required” minlength=”11″ aria-required=”true”>

what’s wrong, why doesn’t work…i can post the form even with one characters
thank sin advance manner

https://www.ads-software.com/plugins/minimum-length-for-contact-form-7/