NPC Random Walking Script- Help?

So, i need some animals that walk around randomly in my game. I've accomplished the task of getting the script to make regular humanoids walk around randomly, but i can't seem to get my animals to function with the script. HELP! Here it is:

while true do
wait(5)
game.Workspace.Character["Humanoid"]:MoveTo(Vector3.new(math.random(1,50),math.random(1,50), math.random(1,50)), game.Workspace.PrimaryPart)
end

NOTE: The script works perfect with any regular robloxian humanoid but fails to work when put into an animal model such as my "Elephant" model. (Yes the elephant is welded) PLEASE HELP!