jQuery倒计时datetime不起作用

Question

我用jQuery在datetime值之间写倒计时。但是这段代码没有打印任何页面。日期时间值$_endDateTime和$_startDateTime来自2017-04-30 23:55:32格式的包含页面。

<!--
Creator: Ahmet ÇELİKEZER
Date: 30.04.2017
Variables Needed: $_endDateTime , $_startDateTime
-->
<?php
$dif_int = strtotime($_endDateTime) - strtotime($_startDateTime); //Diffrance between dates as interval
?>
<script>
$(function(){
var secLeft=<?php echo $dif_int; ?>;
var minLeft=0;
var hourLeft=0;
var dayLeft=0;
$.countBack=function()
{
  if(secLeft>1)
  {
    secLeft--;
    //Split Days,Hours,Minutes,Seconds
    /*
     1Day=86400 Sec
     1Hour=3600 Sec
     1Minute=60 Sec
     1Second=1 Sec
    */
    if(secLeft>86400)
    {
      dayLeft=secLeft / 86400;
      secLeft=secLeft % 86400;
    }
    if(secLeft>3600)
    {
      hourLeft=secLeft / 3600;
      secLeft=secLeft % 3600;
    }
    if(secLeft>60)
    {
      minLeft=secLeft / 60;
      secLeft=secLeft % 60;
    }
    $("#printTime").Text(dayLeft+" Gün "+hourLeft+" Saat "+minLeft+" Dakika "+secLeft+" Saniye");
  }
  else {
    {
      //Time Ended

    }
  }
}
setInterval("$.countBack()",1000);
})
</script>
<p id="printTime"></p>