What sort of top feeder are you using?
When you say you have you have a lot of dead bees in it, do you mean the part the bees access or the main body of the feeder? If flying bees from that hive or another can access the syrup in the main storage part of the feeder (rather than limited access part) they will try to rob it and often get caught in the thick syrup and then perish.
Depending on the design, a slightly dislodged lid or not properly sealed crownboard over the top can allow bees to smell the syrup and drown in their dozens / hundreds or even thousands. Its distressing to discover certainly but hopefully a mistake made only the once..
I would doubt the Hive Alive, if you followed the instructions as you say has much to do with it as a supplement in the syrup.
