If the cast always fail you will never be able to call the “begin” function. And it’s useless that you connect the cast failed to the begin function node, because if the Engine can’t access to that object it won’t be able to call the function.
After OnActorBeginOverlap try to control if the “OtherActor” is “plewp”, and with a “branch” node in the false direction try to print a message. If you see that message than you will never be able to use the “cast” because the actor is not “plewp”. Hope that you understand what i said because i’m not english.