Why wont the seat make the funcion clear?

so bassicly whenever is it i want it to make a sound and when i leave the seat its makes a sound but it doesnt work

local a = script.Parent.Unsits
local b = script.Parent.Sits
local c = script.Parent


	

if c.Occupant ~= nil then
		b:Play()
		
	end
	if c.Occupant == nil then
		a:Play()
	end