the mySQL database will only accept the date in the format of yyyy-mm-dd.
the line of code that is setting up the insert is:
$WA_fieldValuesStr = "".((isset($_POST["id"]))?$_POST["id"]:"") ."" . "|" . "".((isset($_POST["Date"]))?$_POST["Date"]:"") ."" . "|" . "".((isset($_POST["Name"]))?$_POST["Name"]:"") ."";
you can edit this to convert the date you enter to the proper format using the strtotime() and date() functions:
$WA_fieldValuesStr = "".((isset($_POST["id"]))?$_POST["id"]:"") ."" . "|" . "".((isset($_POST["Date"]))?date("Y-m-d", strtotime($_POST["Date"])):"") ."" . "|" . "".((isset($_POST["Name"]))?$_POST["Name"]:"") ."";