# Calculated Layer and messaging

Hi,

trying something new again. I have a piece with the Layer trait, and I want to let the layers follow an expression value: The layer should switch if the deck FateChits is down to a certain number of cards (halfway through the 24-card-deck, to be precise).
This works, in a way, even if I do not understand the logic.
Follows Expression = AggravationLevel → this is a Calculated Property on the same piece: If(FateChits_numPieces<=12,1,2)
Level 1 = 1
What happens: when the cards are <=12, I see level 2. When the cards are >=13, I see level 1. Huh? Reverse logic?
The result is the same if I put the IF clause directly into the layer expression.

OK, I can easily work around that: If(FateChits_numPieces<=12,2,1) works as intended, though different from the logic I understand.

Next q.: I want to report the Layer change. Doing that if I change the level by menu/key is no problem. But “follows expression” does not send a key command, right? Is there a way to do this?