Ajax and setInterval() to auto update text file is not updating

I have two text files that are being display on a web page through ajax. I need these two files to update as soon as more text is added to the text file. When I completed this script I tested it on my localhost and all was working properly. Now I have attempted to get it to work on my web host and the text is displaying, but when it is time to update the files nothing updates.
I tried disabling the caching of the ajax response, but the files still do not update.

Here is the code:

<html>
<head>
<script>
$.ajaxSetup ({
cache: false
});

  function UpdateDAU()
    {
    var xmlhttp;
    if (window.XMLHttpRequest)
      {
      xmlhttp=new XMLHttpRequest();
      }
    xmlhttp.onreadystatechange=function()
      {
      if (xmlhttp.readyState==4 && xmlhttp.status==200)
        {
           document.getElementById("UpdateD").innerHTML=xmlhttp.responseText.split('\n').join('<br/>';
        }
      }
    xmlhttp.open("GET","../logs/dau.txt",true);
    xmlhttp.send();
    }

    function UpdateFireBox()
    {
    var xmlhttp;
    if (window.XMLHttpRequest)
      {
      xmlhttp=new XMLHttpRequest();
      }
    xmlhttp.onreadystatechange=function()
      {
      if (xmlhttp.readyState==4 && xmlhttp.status==200)
        {
        document.getElementById("UpdateF").innerHTML=xmlhttp.responseText.split('\n').join('<br/>');
        }
      }
    xmlhttp.open("GET","../logs/firebox.txt",true);
    xmlhttp.send();
    }


    </script>
</head>
<body>
    <script type="text/javascript">
    UpdateDAU();
    </script>
    <div id="UpdateD">No Logs</div>
    <script type="text/javascript">
    setInterval("UpdateDAU", 1000);
    </script>

    <script type="text/javascript">
    UpdateFireBox();
   </script>
<div id="UpdateF">No Logs</div>
    <script>
    setInterval("UpdateFireBox", 1000);
    </script>

</body>
</html>

Is there something that needs to be changed on the server or is this an issue with my code?
What am I doing wrong?

Solution

After researching for the past week I finally have the display updating properly. I could not get the files to update from the text file, so I had to echo the files from a php file before the ajax displayed it.
This is the code that is working on multiple machines:

<html>
<head>
<script>
$.ajaxSetup ({
// Disable caching of AJAX responses */
cache: false
});

  function UpdateDAU()
    {
    var xmlhttp;
    if (window.XMLHttpRequest)
      {
      xmlhttp=new XMLHttpRequest();
      }
    xmlhttp.onreadystatechange=function()
      {
      if (xmlhttp.readyState==4 && xmlhttp.status==200)
        {
        document.getElementById("UpdateD").innerHTML=xmlhttp.responseText.split('\n').join('<br/>');
        }
      }
    xmlhttp.open("GET","getdau.php",true);
    xmlhttp.send();
    setTimeout(function() {
    UpdateDAU();       
    }, 1000)
    }

    function UpdateFireBox()
    {
    var xmlhttp;
    if (window.XMLHttpRequest)
      {
      xmlhttp=new XMLHttpRequest();
      }
    xmlhttp.onreadystatechange=function()
      {
      if (xmlhttp.readyState==4 && xmlhttp.status==200)
        {
        document.getElementById("UpdateF").innerHTML=xmlhttp.responseText.split('\n').join('<br/>');
        }
      }
    xmlhttp.open("GET","getfirebox.php",true);
    xmlhttp.send();
    setTimeout(function() {
    UpdateFireBox();       
    }, 1000)
    }


    </script>
</head>
<body>
    <script type="text/javascript">
    UpdateDAU();
</script>
<div id="UpdateD"><p class="text-warning">If there is no page...<br> Then the guards have not started there rounds.</p></div>

    <script type="text/javascript">
    UpdateFireBox();
</script>
<div id="UpdateF"><p class="text-warning">If there is no page...<br> Then the guards have not started there rounds.</p></div>

</body>
</html>

Here is the PHP files used to diplay files:

<?php
$file = file_get_contents('../logs/dau.txt', true);
echo $file;
?>

and second PHP file is the same:

<?php
$file = file_get_contents('../logs/firebox.txt', true);
echo $file;
?>

Using this code the logs inside txt files are updated and displayed every second without refreshing the page.

If there is a way to use these same steps but with only 1 php file instead of 2 show me and I will delete my answer and select yours.