attempt to index nil with 'FindFirstChild'?

game.ReplicatedStorage.GiveMoney.OnServerEvent:Connect(function()
	game:GetService("Players"):FindFirstChild(script.Parent.Parent.StarterGui.ControlPlayersGUI.CurrencyController.CashGiver.PlayerName.Text):FindFirstChild("leaderstats"):FindFirstChild("Cash").Value = game:GetService("Players"):FindFirstChild(script.Parent.Parent.StarterGui.ControlPlayersGUI.CurrencyController.CashGiver.PlayerName.Text):FindFirstChild("leaderstats"):FindFirstChild("Cash").Value - tonumber(script.Parent.Parent.StarterGui.ControlPlayersGUI.CurrencyController.CashGiver.Amount.Text) -- The error line
end)

Server-Sided script: (Fixed!)

-- Cash

script.Parent.GiveCash.OnServerEvent:Connect(function(o, player, amt)
	game.Players[player].leaderstats.Cash.Value = game.Players[player].leaderstats.Cash.Value + amt
end)

script.Parent.RemoveCash.OnServerEvent:Connect(function(o, player, amt)
	game.Players[player].leaderstats.Cash.Value = game.Players[player].leaderstats.Cash.Value - amt
end)

-- Rebirths

script.Parent.GiveRebirths.OnServerEvent:Connect(function(o, player, amt)
	game.Players[player].leaderstats.Rebirths.Value = game.Players[player].leaderstats.Rebirths.Value + amt
end)

script.Parent.RemoveRebirths.OnServerEvent:Connect(function(o, player, amt)
	game.Players[player].leaderstats.Rebirths.Value = game.Players[player].leaderstats.Rebirths.Value - amt
end)

Here is the local script for giving cash: (Fixed!)

script.Parent.MouseButton1Click:Connect(function()
	local player = script.Parent.Parent.PlayerName.Text
	local cash = script.Parent.Parent.Amount.Text
	script.Parent.Parent.Parent.GiveCash:FireServer(player,cash)
end)