Attempt to concatenate instance with string?

Hello there! I'm currently having trouble with my morph into player script. The main handler throws an error: attempt to concatenate instance with string.

Here is the remote function code:

local remoteFunction = game.ReplicatedStorage:FindFirstChild("requestPlayerStatus")
local HttpProxy = require(game.ServerScriptService.HttpProxyService:Clone())

    remoteFunction.OnServerInvoke = function(Id)
    local data = game.HttpService:JSONEncode(HttpProxy:GetAsync("http://api.roblox.com/users/" .. Id .. "/onlinestatus"))
    if not data.IsOnline then
        return "offline"
    end
    if data.IsOnline then
        return "online"
    end
end

The GUI local script code:

local plrStatus = game.ReplicatedStorage.requestPlayerStatus:InvokeServer(script.Parent.Parent.Parent.UserId.Value)

if plrStatus == "offline" then
    script.Parent.TextColor3 = Color3.fromRGB(85, 255, 0)
    script.Parent.Text = "Online"
end

if not plrStatus == "offline" then
    script.Parent.TextColor3 = Color3.fromRGB(255, 0, 0)
    script.Parent.Text = "Offline"
end

I've looked through every devforum post mentioning this error. I apply the solution to my code unfortunately it does not change anything and still throws an error. I've tried everything I could possibly thing of. tostring() didn't work. tonumber() didn't work. I have absolutely no idea how to troubleshoot my code.

Any ideas?