Zombie.Humanoid.Health will not change! No scripting errors, please help?

Hey guys, My latest problem involves the normal roblox zombie, fully equipped with a humanoid named "Zombie". Anyway I wanted to edit a zombies health to a value * #players (as well as the maxhealth). I made a script and the maxhealth changed fine but the health refused to budge from 100, sometimes the zombies just straight up died on spawn (1/50 chance of that happening, no clue why but that isn't really relevant). I am hoping this is a well known issues with obvious workarounds. I have no scripting errors and am 100% certain of that, there is no output and this appears to be a random bug!

Basically my question is: Is there a reliable (working) way of changing the zombie's humanoid's health through scripts?

EDIT: I just tried manually setting the zombie's health to something other than 100, it stays at 100 still, when I went play solo and edited it live the client crashed, zzzz.