Reading the error message

добрый вечер коллега, скажите какой у вас именно контроллер, проблема очень легко решаема

Quote from XxOnlyInstinctsxX

This is the controller I'm using, do you need some more information?

Что?

Quote from XxOnlyInstinctsxX

IF (Buffer[])==(Substring[])

That won't work. That's not searching for Substring inside Buffer, it's looking for a complete match -- every character in one string exactly matching every character in the other string.

It's like programming IF 1==1.00000001 THEN   
It'll never be True.

Look up the StrFind() function.

to check for specific message one can use function ISMESSAGESET()

for example if message is KSS15004

one can write something simple like this, perhaps in Submit:

$OUT[666]=IsMessageSet(15004)

more general approach is to use function GET_MSGBUFFER()

this gets info on all messages that are in the message buffer. however, this requires more processing, message test may not be retrieved etc.