Why does an error occur when starting external processing 1C through OLE?

Question

Delphi

There is a task from a program in Delphi through OLE to connect to the 1C database and start external processing. I connect using V83.Application. The connection is created, the processing is loaded, the desired function is launched. But in it there is a completely incomprehensible error to me. The function is located in the external processing object module. Here is the function itself (I threw out everything superfluous, the error is reproduced):

Функция СтартЗагрузки(парНастройки) Экспорт
  ФайлНастройки = Новый Файл(парНастройки);
  Если Не ФайлНастройки.Существует() Тогда
    Возврат "Файл не существует";
  КонецЕсли;
  Возврат "Ок!";
КонецФункции

A string with the full file name is passed to parSettings.
I get this error:
{ExternalProcessing.MyProcessing.ObjectModule(30)}:
Value is not an object type value (Exists)
What am I doing wrong?
Checked the type of the FileSettings variable. Expected "File", but it turned out to be "String". That there is no method is not surprising. But why String?

Answer 1

FileSettings by any chance not a processing form prop with string type?