Агент в Bitrix не создает файл

class SectionExportAgent{
    public static function SectionExport(){
        if(CModule::IncludeModule('iblock') and CModule::IncludeModule('fileman')){           

            $fp = fopen('sections_export.csv', 'w');
            fwrite($fp, "ID_GROUP;IC_GROUP0;IC_GROUP1;IC_GROUP2". "\r\n");

            $arFilter = Array('IBLOCK_ID'=>17, 'ACTIVE'=>'Y', 'DEPTH_LEVEL'=>1);
            $db_list = CIBlockSection::GetList(Array(), $arFilter, true);

            while($ar_result = $db_list->GetNext())
            {                
                $str=$ar_result['ID'].";".$ar_result['NAME'].";";
                fwrite($fp, $str. "\r\n");

                $rsParentSection = CIBlockSection::GetByID($ar_result['ID']);
                if ($arParentSection = $rsParentSection->GetNext())
                {
                    $arFilter2 = array('IBLOCK_ID' => $arParentSection['IBLOCK_ID'],'>LEFT_MARGIN' => $arParentSection['LEFT_MARGIN'],'<RIGHT_MARGIN' => $arParentSection['RIGHT_MARGIN'],'DEPTH_LEVEL' => 2); // выберет потомков без учета активности
                    $rsSect = CIBlockSection::GetList(array('left_margin' => 'asc'),$arFilter2);
                    while ($arSect = $rsSect->GetNext())
                    {
                        $str=$arSect['ID'].";".$ar_result['NAME'].";".$arSect['NAME'].";";
                        fwrite($fp, $str. "\r\n");

                        $rsParentSection2 = CIBlockSection::GetByID($arSect['ID']);
                        if ($arParentSection2 = $rsParentSection2->GetNext())
                        {
                            $arFilter3 = array('IBLOCK_ID' => $arParentSection2['IBLOCK_ID'],'>LEFT_MARGIN' => $arParentSection2['LEFT_MARGIN'],'<RIGHT_MARGIN' => $arParentSection2['RIGHT_MARGIN'],'DEPTH_LEVEL' => 3); // выберет потомков без учета активности
                            $rsSect2 = CIBlockSection::GetList(array('left_margin' => 'asc'),$arFilter3);
                            while ($arSect2 = $rsSect2->GetNext())
                            {
                                $str=$arSect2['ID'].";".$ar_result['NAME'].";".$arSect['NAME'].";".$arSect2['NAME'].";";
                                fwrite($fp, $str. "\r\n");
                            }
                        }

                    }
                }
            }

            fclose($fp);
            return 'SectionExportAgent::SectionExport();';
        } else{
            return 'SectionExportAgent::SectionExport();';
        }

    }
}