I’m not sure why the function does not work, but it looks like your date format is not US English – maybe the function misses your date format. Can you try right clicking the calendar icon and selecting inspect and show me a snippet like the one attached.
To work around this you can modify the function replacing the two first variables with this:
var r1 = jQuery("#dffs_DateColumn1 input").val().split("/");
var d1 = new Date(r1[2],(r1[1]-1),r1[0]);
var r2 = jQuery("#dffs_DateColumn1 input").val().split("/");
var d2 = new Date(r2[2],(r2[1]-1),r2[0]);
Alexander
