This is a glitch with VCE. It is easily fixed, just do this instead:
OnActivate > Self > ModVariable > "Brick" "temp" "Set" "<var:pl:damage>"
OnActivate > Self > ModVariable > "Brick" "temp" "Add" "25"
OnActivate > Player > ModVariable > "Damage" "Set" "<var:br:temp>"
Modifying special variables with VCE is very glitchy. It only works if you are setting the variable. Be careful that you don't go above 100 damage (or the maxDamage of the playertype), it causes a weird glitch which deletes (I think) players until they either disconnect, respawn, or join a minigame. Also, lets hope not too many trolls hear about this glitch. Lets just say its the better one of the two i know..