ArrayCollection not refreshed within loop
public function myFunc():void{

    for (roller = 0; roller < customizedFields_array.length; roller++) {
        var newCol:FlexDataGridColumn = new FlexDataGridColumn();
        remote_obj.getYN(customizedFields_array.getItemAt(roller).FLD);
        newCol.filterComboBoxDataProvider = _YN;
        newCol.filterComboBoxLabelField =customizedFields_array.getItemAt(roller).FLD;
        newCol.filterComboBoxDataField =customizedFields_array.getItemAt(roller).FLD;
        }
        cols.push(newCol);
    }
        myDataGrid.columns = cols;
}

public function getYN_result(event:ResultEvent):void{
    _YN = event.result as ArrayCollection;
}

customizedFields_array.refresh();  // refresh the array collection
myDataGrid.invalidateDisplayList();// refresh the datagrid