How to stop datastore returning a string?

For some reason my datastore is returning " " and I keep getting errors about an attempt to compare a string with a number.

Code:

local DSS = game:GetService("DataStoreService")
ArrestDS = DSS:GetDataStore("Arrest")
game.Players.PlayerAdded:Connect(function(plr)
	local plra = Instance.new("StringValue")
	plra.Name = plr.Name
	plra.Parent = script.Folder
	local Time = ArrestDS:GetAsync(plr.Name .. ":" .. plr.UserId)
	print(Time)
	if Time == " " or Time == nil or Time == "" then
		ArrestDS:SetAsync(plr.Name .. ":" .. plr.UserId, tonumber(0))
	elseif Time > 0 then
		local jailgui = script.JailUI:Clone()
		jailgui.Parent = plr.PlayerGui
		plr.TeamColor = BrickColor.new("Magenta")
	end
end)

game.ReplicatedStorage.Cuffs.OnServerEvent:Connect(function(plr, otherplr, state, arresttime)
	if state == "Cuff" then
		script.Folder:FindFirstChild(plr.Name).Value = otherplr
		cuff(plr, otherplr)
	elseif state == "Uncuff" then
		script.Folder:FindFirstChild(plr.Name).Value = ""
		uncuff(plr, otherplr)
	end
	if state == "Arrest" then
		local jailgui = script.JailUI:Clone()
		jailgui.Parent = game.Players[otherplr].PlayerGui
		game.Players[otherplr].TeamColor = BrickColor.new("Magenta")
		ArrestDS:SetAsync(otherplr .. ":" .. game.Players[otherplr].UserId, arresttime)
		while wait(1) do
			local success = pcall(function()
				return ArrestDS:IncrementAsync(otherplr .. ":" .. game.Players[otherplr].UserId, -1)
			end)
			print(ArrestDS:GetAsync(otherplr .. ":" .. game.Players[otherplr].UserId))
		end
	end
end)

function cuff(plr,otherplr)
	game.Workspace[otherplr].Torso.Anchored = true
	game.Workspace[otherplr].Torso.CanCollide = false
	game.Workspace[otherplr].Head.CanCollide = false
	game.Workspace[otherplr].Torso.Anchored = false
	while script.Folder:FindFirstChild(plr.Name).Value == otherplr do
		wait(0.00000001)
		game.Workspace[otherplr].Torso.CFrame = game.Workspace[plr.Name].Torso.CFrame * CFrame.new(0,0,-2.5)
	end
end

function uncuff(plr,otherplr)
	game.Workspace[otherplr].Torso.CanCollide = true
	game.Workspace[otherplr].Head.CanCollide = true
end