即使响应状态为200 OK，AJAX也会触发ERROR功能

I don't understand why this is returning the Error function from AJAX. I had it working a few days ago and I don't know how it's failing now. I even super simplified my code to try to fire the success and rebuild the rest.

This is my Jquery:

$("#results").click(function() {
  $.ajax({
    url: "http://www.URL.php",
    type: "POST",
    data: {
      ajaxval: "A"
    },
    dataType: 'text',
    success: function(data) {
      alert(data);
      alert("success");
    },
    error: function() {
      alert("fail");
    }
  });
});

This is my PHP:

<!DOCTYPE html>
<html>

<body>


<?php

$ajaxnum = $_POST['ajaxval'];

echo $ajaxnum;
?>


</body>
</html>

Seems super simple, Please let me know if I'm somehow missing something. Like I said I had a much more complex php returning an html table by way of echoing rows back from a mySQL query result using a loop, etc.

enter image description here