I don't know exactly why.
Here is another code sample that may help making use of your:
id="make_payment"
<!doctype html>
<html lang="en">
<head>
<meta charset="utf-8">
<title>submit demo</title>
<script src="
https://ajax.googleapis.com/ajax/libs/jquery/2.2.4/jquery.min.js"></script></head>
<body>
<form method="post" id="auctionform">
<div>
<input type="text" class="form-control btn-block" id="qty" name="qty" placeholder="Amount">
<button type="button" id="make_payment" class="btn btn-default btn-block">MAKE PAYMENTS</button>
</div>
</form>
<div id="msgs"></div>
<script>
$("#make_payment").on("click", function(event) {
var myqty=$("#qty").val();
var min_bid=5200;
if( myqty < min_bid){
event.preventDefault(); // don't submit this
$('#msgs').html("<p>bad input to low</p>");
}else
{
$.ajax({
url: 'bids.php',
data: {qty: myqty},
error: function() {
$('#msgs').html("<p>ajax error</p>");
},
success: function(data) {
console.log(data);
$('#msgs').html("<p>SUCCESS: You sent this to the server " + data + '</p>');
},
type: 'POST'
});
}
});
</script>
</body>
</html>
and bids.php is:<?php
echo $_POST["qty"];
?>