Cell width changed after calling fnAddData

Hello ,
I have this DataTable Aboject :

$('#tbl').dataTable({
                "sDom": 'T<"clear">lfrtip',
                "aoColumns": [
                    { "sWidth": "1px" }, { "sWidth": "150px" }, { "sWidth": "150px" }, { "sWidth": "150px" }, { "sWidth": "150px" }
                    
                ],
                
                "oTableTools": {
                    "aButtons": [],
                    "sRowSelect": "single"
                },
                "oLanguage": {
                    "sEmptyTable": "<div style='color:red'>No Records</div>",
                    "oPaginate": { "sPrevious": "@_Layout.Prev ", "sNext": "@_Layout.Next" }
                },
                "bLengthChange": false,
                "bFilter": false,
                "bSort": false,
                "bInfo": false,
                "bAutoWidth":false
            });

now the table is empty and all cell width is looks as i want , when i try to add a new record using the fnAddData all width of the cells take the same width , how could i fix the width of these new record cells

thank you