Why doesn't the StrFind() function work?

Question

1C-Enterprise

1C 8.3.9, SCP 1.3 (regular application).
Compatibility mode - 8.2.13.
Here is a problem with the StrFind() function:

How to cure?

Answer 1

1) turn off compatibility mode
2) write your own search function, which will search in a loop until the searched substring is found and the last found will be the first from the right.

Answer 2

What errors are shown in the logs?