Reply To: [Waiting for user confirmation] number of selections in checkboxes

Thanks, actually I did the following:
[cred_field field="expertise" display="checkbox"]
[cred-show-group if="(LEN($(expertise)) gt 3)" mode="fade-slide"]
<strong><div style="color: red;">YOU HAVE SELECTED MORE THAN 3 TYPES! ( unselect one choice). </div></strong>
[/cred-show-group]
This code did almost what I want: it shows the error message if I select more than 3 checkboxes, however it does not desactivate the submit button. Any idea how I van do it please?