Part only moves to the mouse once?

Ok so ive got a script so when u hold down q it would make a beam depending on where your mouse cursor is but i have a problem it only moves the mouse once then stops and doesnt move again how can i fix this?

local on = false
script.Remotes.On.OnServerEvent:Connect(function(plr,mouse)
	on = true
	local folder = Instance.new("Folder",workspace.Beams)
	folder.Name = plr.Name
	local endpart = Instance.new("Part",folder)
	endpart.Size = Vector3.new(0.99, 0.99, 0.99)
	endpart.Anchored = true
	local beam = script.Stuff.Beam:Clone()
	beam.Parent = plr.Character.LeftHand
	local att1 = Instance.new("Attachment",plr.Character.LeftHand)
	local att2 = Instance.new("Attachment",endpart)
	beam.Attachment0 = att1
	beam.Attachment1 = att2

	while on == true do
		local posx,posy,posz = mouse.X,mouse.Y,mouse.Z
		endpart.Position = Vector3.new(posx,posy,posz)
		wait()
	end
end)

script.Remotes.Off.OnServerEvent:Connect(function(plr)
	workspace.Beams[plr.Name]:Destroy()
	on = false
	plr.Character.LeftHand.Beam:Destroy()
	plr.Character.LeftHand.Attachment:Destroy()
end)