Why can't R-15 Meshes can't be changed with a script?

Okay, so my friend and I have been working with R-15 and we can't figure out why we can't change the mesh ID on the different parts!

here is what I have made so far ... and it doesn't work ... (this script is in an ImageButton that is inside a Frame, that is inside a ScreenGui, that is inside StarterGui) (also, you spawn with R-15 in this game so all these parts are inside the Player)

victim = script.Parent.Parent.Parent.Parent.Parent.Character

function kill()

    script.Parent.Parent:Destroy()

--Character Meshes
LeftFoot = victim.LeftFoot
LeftFoot.MeshID = ("http://www.roblox.com/asset/?id=542649994")

LeftHand = victim.LeftHand
LeftHand.MeshID = ("http://www.roblox.com/asset/?id=542649942")

LeftLowerArm = victim.LeftLowerArm
LeftLowerArm.MeshID = ("http://www.roblox.com/asset/?id=542649944")

LeftLowerLeg = victim.LeftLowerLeg
LeftLowerLeg.MeshID = ("http://www.roblox.com/asset/?id=542650004")

LeftUpperArm = victim.LeftUpperArm
LeftUpperArm.MeshID = ("http://www.roblox.com/asset/?id=542649949")

LeftUpperLeg = victim.LeftUpperLeg
LeftUpperLeg.MeshID = ("http://www.roblox.com/asset/?id=542650009")

LowerTorso = victim.LowerTorso
LowerTorso.MeshID = ("http://www.roblox.com/asset/?id=542650030")

RightFoot = victim.RightFoot
RightFoot.MeshID = ("http://www.roblox.com/asset/?id=542650013")

RightHand = victim.RightHand
RightHand.MeshID = ("http://www.roblox.com/asset/?id=549545789")

RightLowerArm = victim.RightLowerArm
RightLowerArm.MeshID = ("http://www.roblox.com/asset/?id=549545792")

RightLowerLeg = victim.LeftLowerLeg
RightLowerLeg.MeshID = ("http://www.roblox.com/asset/?id=542650017")

RightUpperArm = victim.RightUpperArm
RightUpperArm.MeshID = ("http://www.roblox.com/asset/?id=549545795")

RightUpperLeg = victim.RightUpperLeg
RightUpperLeg.MeshID = ("http://www.roblox.com/asset/?id=542650023")

UpperTorso = victim.UpperTorso
UpperTorso.MeshID = ("http://www.roblox.com/asset/?id=542649972")

end

script.Parent.MouseButton1Down:connect(kill)

thank you ~Fin