Ajax form form textbox value onsubmit

after submitting the form with ajax i cant set the value correctly in the multiple textbox, here's my form

<form id="searchForm" action="process.php" method="post">
<input id="cust_code" name="cust_code" required>
<input id="cust_code1" name="cust_code1" disabled>
<input id="cust_name" name="cust_name" disabled>

<button type="submit">Search</button>
</form>

      

        
        
        
      

    

process.php

$cust_code = $_POST['cust_code'];
$result = mysql_query("SELECT code,cust_name FROM information WHERE code=$cust_code") or die(mysql_error());
$data = mysql_fetch_array($result);

      

        
        
        
      

    

JavaScript:

var formData = {
            'cust_code': $('#cust_code').val()
        };
        $.ajax({
            type        : 'POST',
            url         : 'process.php',
            data        : formData,
            dataType    : 'json',
            encode          : true,
            success: function(data)          // recieved data from process.php
            {
                var code = data[0];              
                var cust_name = data[1];           

                // Update id value
                document.getElementById('cust_code').value = code;
                document.getElementById('cust_code1').value = code;
                document.getElementById('cust_name').value = cust_name;


            }
        })

      

        
        
        
      

    

the value of cust_code and cust_code1 changed after sending, but not for cust_name

any ideas?

EDIT: id was used in another page (php include) to make the input not changed, solved!