can't settext combogrid editor on event onBeginEdit

[Opan Mustopah]

hello again,

why i can't set text on combogrid editor on event onBeginEdit?
here is my code:

Code:

var carrier_id = $(this).datagrid('getEditor',{index:index,field:'carrier_id'});
        var carrier_id_b = $(this).datagrid('getEditor',{index:index,field:'carrier_id_b'});
        console.log(carrier_id);
        console.log(carrier_id_b);
        $(carrier_id.target).combogrid('setText','test');
        $(carrier_id_b.target).textbox('setText','opasdk');
        if (!is_master_detail){
          if (state.row == 'new_row'){
            $(carrier_id.target).combogrid({
              onSelect:function(index,row){
                // AJAX REQUEST
                $.get(init_url,{prm_carrier_id: row.carrier_id},function(data){
                  $(carrier_id_b.target).textbox('setValue',data.val);
                },'json');
              }
            });
          }
        }

when i do that, combogrid still empty,its like combogrid is forced to default value when i setText or set his value,and strangely when i use clear or reset method its working.
but when i try to set text on textbox, it works. my questtion is why?
is there a problem when i put large function on event onBeginEdit?

many thanks for the answer