Why is the variable not defined?

Question

1C

In the example on the left everything works, but in my example it doesn't.

Answer 1

Specify the " &AtClient " directive for the variable:

&НаКлиенте
Перем Сообщ;

&НаКлиенте
Процедура Стартовать(Команда)
  Сообщить(Сообщ);
КонецПроцедуры

Сообщ = "сообщение";

Answer 2

In the example on the left, it is either an object module or a thick client in general. And on the right - a managed form, where the visibility of the client and server was incorrectly marked.