Error when making a possession script, isnt reaching the second OnServerInvoke?

So I have this possession script, its activated when clicking on a player and you possess their character but as a result you lose your original character so theres an empty clone there for you to inhabit after you depossess by pressing R when youre in the other players possessed body, the depossession phase i cant reach though because i have a strange error but first im gonna show all the scripts

localscript in starterplayerscripts

local Players = game:GetService("Players")
local ReplicatedStorage = game:GetService("ReplicatedStorage")
local UserInputService = game:GetService("UserInputService")

local Player = Players.LocalPlayer
local Mouse = Player:GetMouse()

UserInputService.InputEnded:Connect(function(input)
	if input.UserInputType == Enum.UserInputType.Keyboard and input.KeyCode == Enum.KeyCode.R then
		ReplicatedStorage.ReturnPossession:InvokeServer()


	end
	if input.UserInputType ~= Enum.UserInputType.MouseButton1 and Mouse.Target then
		local targetPlayer = Players:GetPlayerFromCharacter(Mouse.Target.Parent)
		if not targetPlayer then return end

		local result = ReplicatedStorage.TakePossession:InvokeServer(targetPlayer)
		if result then
			print(result.Error)

		end
	end
end)


ReplicatedStorage.EnableClientControls.OnClientEvent:Connect(function(enable)
	local controls = require(Player.PlayerScripts.PlayerModule):GetControls()
	if enable then
		controls:Enable(true)
	else
		controls:Disable()
	end
end)

serverscript in serverscriptservice

local ReplicatedStorage = game:GetService("ReplicatedStorage")

local IS_POSSESSED_KEY = "IsPossessed"
local IS_POSSESSING_KEY = "IsPossessing"
local RETURN_CHARACTER_KEY = "ReturnCharacter"

function updateReturnToCharacterValue(character, parent)
	local value = nil
	if parent:FindFirstChild(RETURN_CHARACTER_KEY) then
		value = parent[RETURN_CHARACTER_KEY]
	else
		value = Instance.new("ObjectValue")
		value.Name = RETURN_CHARACTER_KEY
		value.Parent = parent
	end
	value.Value = character
end

ReplicatedStorage.TakePossession.OnServerInvoke = function(player, target)
	if not target:IsA("Player") then
		return {
			Error = "Target is not a player"
		}
	end

	if player == target then
		return {
			Error = "You cannot possess yourself"
		}
	end
	
	if player:GetAttribute(IS_POSSESSED_KEY) then
		return {
			Error = "You are already possessed"
		}
	end

	if player:GetAttribute(IS_POSSESSING_KEY) then
		return {
			Error = "You are already possessing someone else"
		}
	end

	if target:GetAttribute(IS_POSSESSED_KEY) then
		return {
			Error = target.DisplayName .. " is already possessed"
		}
	end

	if target:GetAttribute(IS_POSSESSING_KEY) then
		return {
			Error = target.DisplayName .. " is already possessing someone else"
		}
	end
	
	-- Clone original character and reassign character
	-- (clone is required because character is deleted after Character reassignment)
	local originalCharacter = player.Character
	originalCharacter.Archivable = true
	local originalCharacterClone = originalCharacter:Clone()
	originalCharacterClone.Parent = originalCharacter.Parent
	updateReturnToCharacterValue(originalCharacterClone, player)
	
	-- Assume ownership of the target
	local targetCharacter = target.Character
	targetCharacter.HumanoidRootPart:SetNetworkOwner(player)
	player.Character = targetCharacter
	
	-- Tell the posessed player to seize controls
	ReplicatedStorage.EnableClientControls:FireClient(target, false)
	
	
	--------RETURN POSSESSION
	game.ReplicatedStorage.ReturnPossession.OnServerInvoke()
	
	--possessed player receives back controls
	ReplicatedStorage.EnableClientControls:FireClient(target, true)
	
	--Possessors ownership of target is revoked 
	player.Character = player[RETURN_CHARACTER_KEY].Value
	
	
	
	
	-- Set info on player and target
	player:SetAttribute(IS_POSSESSED_KEY, false)
	player:SetAttribute(IS_POSSESSING_KEY, true)
	
	target:SetAttribute(IS_POSSESSED_KEY, true)
	target:SetAttribute(IS_POSSESSING_KEY, false)
end

now the error is "OnServerInvoke is a callback member of RemoteFunction; you can only set the callback value, get is not available."

and it says this error on line 19 in the localscript

local result = ReplicatedStorage.TakePossession:InvokeServer(targetPlayer)

No idea what it could possibly mean but its preventing my goal of the player being able to depossess

Hiya o/

Your code looks fine, one thing I noticed is your not returning anything if the server has finished the invoke successfully.