attempt to index nil with 'Parent'?

I'm trying to insert an accessory onto the player using LoadAsset and get the hat ID via a textbox but whenever I try to insert the hat it gives me this error: attempt to index nil with 'Parent'. I don't know what is nil. If I change FindFirstChild(plr) in the server script to FindFirstChild(JCAspit) it works. The local script is in the textbox and the server script is in ReplicatedStorage. I can insert gears as well and it works fine but it still gives me the error after it inserts.

Local Script

local assetID = script.Parent
backpack = game.Players.LocalPlayer.Backpack
plr = game.Players.LocalPlayer.Name

script.Parent.FocusLost:connect(
	function(enterPressed)
		if enterPressed then
			--	print(assetID.Text.. " ID was set")
			game.ReplicatedStorage.RemoteFunction:InvokeServer(assetID.Text, backpack, plr)
		--	print(assetID.Text.. " after invoke")
		end
	end)

Server Script

game.ReplicatedStorage.RemoteFunction.OnServerInvoke = function(player, assetID, backpack, plr)
	print(assetID)
	print(plr)
	if plr then
	game:GetService("InsertService"):LoadAsset(assetID):FindFirstChildWhichIsA("Tool").Parent=backpack
	print("Tool inserted")
		
	game:GetService("InsertService"):LoadAsset(assetID):FindFirstChildWhichIsA("Accessory").Parent=workspace:FindFirstChild(plr)
	print("Accessory inserted")
	end	
end