I'm trying to make a trade system but I can't seem to get the PlayerGui?

So I've made the GUI and all, you can click trade and if you click trade it'll send the person you're trying to trade with a Frame saying that somebody wants to trade, but I can't seem to get the other player's PlayerGui. What I thought would fix it was to fire a RemoteEvent from the client to the server, then the server gets the player's PlayerGui and sends it back to the client, but it sends "nil" instead of the GUI. I've even printed if it gets the GUI and it does, but then it sends "nil" instead of the GUI. Please help...

Server script:

game.ReplicatedStorage.RemoteEvents.TradeEvents.GetPlayerGui.OnServerEvent:Connect(function(player,playerToTradeWith)

    local realPlayer

    for _,possiblePlayer in pairs(game.Players:GetPlayers()) do

        if possiblePlayer.Name == playerToTradeWith then

            realPlayer = possiblePlayer
            break
        end
    end

local playerGui = realPlayer:FindFirstChild("PlayerGui")    

    game.ReplicatedStorage.RemoteEvents.TradeEvents.GetPlayerGui:FireClient(player,playerGui)
end)

Client script:

script.Parent.MouseButton1Down:Connect(function()

    local player = game.Players.LocalPlayer
    local playerText = script.Parent.Parent.Text
    local playerToTradeWith

    if game.Players:FindFirstChild(playerText) then

        playerToTradeWith = game.Players:FindFirstChild(playerText)

        if playerToTradeWith == nil then

            script.Parent.Text = "That player isn't in the game!"
            script.Parent.Frame.BackgroundColor3 = Color3.fromRGB(252, 11, 35)
            script.Parent.Background.BackgroundColor3 = Color3.fromRGB(115, 12, 21)

            wait(3)
            script.Parent.Text = "Trade"

            script.Parent.Frame.BackgroundColor3 = Color3.fromRGB(36, 255, 99)
            script.Parent.Background.BackgroundColor3 = Color3.fromRGB(16, 111, 47)

        else

            game.ReplicatedStorage.RemoteEvents.TradeEvents.GetPlayerGui:FireServer(playerText)
        end
    end
end)

game.ReplicatedStorage.RemoteEvents.TradeEvents.GetPlayerGui.OnClientEvent:Connect(function(plrGui)

    local player = game.Players.LocalPlayer

    print(plrGui.Parent)

    if plrGui:WaitForChild("Guis").TradeGui.TradeRequest.IsBusy.Value == false then

        plrGui:WaitForChild("Guis").TradeGui.TradeRequest.IsBusy.Value = true

        plrGui:WaitForChild("Guis").TradeGui.TradeRequest.PlayerName.Text = player.Name.." wants to trade with you"
        plrGui:WaitForChild("Guis").TradeGui.TradeRequest.PlayerWantingToTrade.Value = player.Name
        plrGui:WaitForChild("Guis").TradeGui.TradeRequest.Visible = true

        script.Parent.Text = "Trade Sent"
        script.Parent.Frame = Color3.fromRGB(141, 24, 255)
        script.Parent.Background = Color3.fromRGB(62, 16, 108)
    else
        script.Parent.Text = "That player is busy right now!"
        script.Parent.Frame.BackgroundColor3 = Color3.fromRGB(252, 11, 35)
        script.Parent.Background.BackgroundColor3 = Color3.fromRGB(115, 12, 21)

        wait(3)
        script.Parent.Text = "Trade"

        script.Parent.Frame.BackgroundColor3 = Color3.fromRGB(36, 255, 99)
        script.Parent.Background.BackgroundColor3 = Color3.fromRGB(16, 111, 47)
    end
end)