How to force player to be seated?

I am trying to make a script that will force the player to be seated during a cutscene, but the script I am using does not work?

-- Roblox services
local Workspace = game:GetService("Workspace")

-- Variables
local seat = script.Parent
local Classroom3 = seat.Parent.Parent
local seatOccupant = seat.Occupant
local CutscenePlayed = Classroom3:WaitForChild("CutscenePlayed")
local CutsceneScript = Classroom3:WaitForChild("cutsceneScript")

print("Test 1")

local function startCutscene()
	
	print("Test 2")
	
	if CutscenePlayed.Value == false then
		
		CutsceneScript.Disabled = false
		
		while true do
			
			wait(0.1)
			
			seatOccupant.Sit = true
			
		end
		
	end
	
seat:GetPropertyChangedSignal("Occupant"):Connect(startCutscene)

When I run this code, I get this error message: Attempt to index nil with 'Sit'

I don't really understand the error message. I know what nil is, but indexing?

All help will be appreciated greatly!

EDIT: I tried to print seatOccupant, but it printed nil.

Your missing something very simple. The character doesn't have a sit value. The Humanoid has a sit value

Try this

-- Roblox services
local Workspace = game:GetService("Workspace")

-- Variables
local seat = script.Parent
local Classroom3 = seat.Parent.Parent
local seatOccupant = seat.Occupant
local CutscenePlayed = Classroom3:WaitForChild("CutscenePlayed")
local CutsceneScript = Classroom3:WaitForChild("cutsceneScript")

print("Test 1")

local function startCutscene()

    print("Test 2")

    if CutscenePlayed.Value == false then

        CutsceneScript.Disabled = false

        while true do

            wait(0.1)

            seat:Sit(InputPlayerHumanoid)

        end

    end

seat:GetPropertyChangedSignal("Occupant"):Connect(startCutscene)

this is assuming that seat is some sort of a seat instead of a normal part