Thannks for your answer. Now It is more clear for me.
There is one more issue, even I activate tolerance key ST, without pressing simulation button, it is not triggering with FM you've said above.
Is this normal system behavior? I mean that If user enter invoice and post it directly without simulating, tolerance key ST is bypassed. Is this an error?
Edit: I've checked direct posting. User can't bypass it but the issue is that there was no message about blocking. If user press simulate button and play with dates someting is calculated again and traffic light turns yellow and saying "correct but blocked". So the user can understand that there is blocking reason. But without simulation button and playing with dates, user always see traffic light as green.