map blueprint not working after a while.
You don’t need to cast, that’s what the blue line means.
Also, save this
In a variable and access is from there, not from the begin play execution line.
no still not working it works at first but doesn’t work after a few seconds
I’m sure you don’t need all the code on tick. You want to destroy those actors, set materials and play a sequence, EVERY FRAME? 
Maybe explain what you’re trying to do?