jQuery UI datepicker: Displaying 1969 although I use strtotime

Question

I have PHP+JQUERY room reservation application. I'm using the datepicker widget for picking date and I encounter a problem. I try to convert the selected date (in dd/mm/yyyy format) to YYYY-mm-dd format in order to INSERT it to my database. When I pick the first dates, it converts well but when I pick other dates, I see the date 1969-12-31. Here is my JQUERY code:

    $(function() {
    $( "#datepicker" ).datepicker({ 
        showOn: "button",
        buttonImage: "images/calendar.gif",
        buttonImageOnly: true,          
        minDate: 0, 
        maxDate: "+3W", 
        dateFormat: "dd/mm/yy",
        beforeShowDay: function (date) {
        var day = date.getDay();
        return [(day == 0 || day == 1 || day == 2 || day == 3 || day == 4), ''];
        },
        onSelect: function(dateText) {
            $("#registration").load("room.php #registration", {selectedDate: dateText}, function() { 
                $( "input:submit, a, button", ".registration" ).button();
                $( "a", ".registration" ).click(function() { return false; });
            });

        }

    });
    });  

And then i echo the result for testing:

    <?php if(isset($_POST['selectedDate']))
           { 
              $selectedDate=$_POST['selectedDate']; 
              echo date('Y-m-d',strtotime((string)$selectedDate)); 
           } 
    ?>

Here is an image in my app: http://oi43.tinypic.com/29tv2c.jpg

1:

Answer 1

Eventually i by passed the problem. instead of converting it in PHP, i converted it in JS:

        onSelect: function(dateText) {

        //Converting the date format by spliting the date.
        var dt= dateText;
        var arrDt = dt.split('/');
        var newDt = arrDt[2] + "-" + arrDt[1] + "-" + arrDt[0];

        //Loading the rooms div acoording to the sent selected date in JSON format  
            $("#registration").load("room.php #registration", {selectedDate: newDt}, function() { 
                $( "input:submit, a, button", ".registration" ).button();
                $( "a", ".registration" ).click(function() { return false; });
            });

        }

But i still don't know what caused the date() function conversion problem!