Dynamic Columns

Error messages shown:
DataTables warning: table id=listeFWRU - Requested unknown parameter '3' for row 5923, column 3. For more information about this error, please see https://datatables.net/tn/4
Description of problem:
Columns limite to 7 while there are more

hello, I am discovering the datatable and the code to make the columns dynamic.
I try things and get inspired by what I find.

This is my code
$(document).ready(function() {

var columns = []; 
$.ajax({
        // "url": "static/objects2.txt", // This works for a static file
        url: "/fwru/get",
        dataType: "json",
        columnDefs: [{
        "defaultContent": "-",
        "targets": "_all"
        }],
        scrollCollapse: true,
        scrollY: true,
        scrollX: true,
        dataSrc: "",
        success: function (data) {
            var columns = [];
            //build the DataTable dynamically.
            columnNames = Object.keys(data[0]); //.Table[0]] refers to the propery name of the returned json
            for (var i in columnNames) {
                columns.push({
                    data: columnNames[i],
                    title: "Cond"+columnNames[i]
                });
            }

            $('#listeFWRU').DataTable({
                data: data,
                rowId: 'ImportID',
                scrollX: true,
                columns: columns
            });
            }
        })
    });

And on the screen I've not all the columns

On letf I've 7 columns. On the right, in the json I've have more columns.

Where are theses ?

Thanks in advance for your device and sorry for my english, I hope ma question is comprehensive.