Roblox Lerping | Why this show a error "Argument 3 missing or nil"?

Code:

local self = {}

function self:StartEnemy(source, enemy)
	local stats = require(game.ReplicatedStorage.Modules.Types.EnemyStats)
	
	
	stats = stats[enemy]
	
	local obj = game.ReplicatedStorage.Assets.Enemies[enemy]:Clone()
	obj.CFrame = source["StartingPoint"].CFrame
	
	for i=1,#source,1 do
		local scf = obj.CFrame
		for j=0,1,stats.Speed*0.002 do
			local target = source[i].CFrame.p+Vector3.new(0,obj.Position.Y-1161.438,0)
			print(target)
			print(source[i])
			obj.CFrame = scf:lerp{target,i}
			wait(0.01)
		end
	end
end


return self

Output:

-839.400085, 1163.56262, 455.549927
  Path
  16:57:58.552 - Argument 3 missing or nil
16:57:58.552 - Stack Begin
16:57:58.553 - Script 'ServerScriptService.Modules.Classes.Enemy.EnemyAI', Line 18 - method StartEnemy
16:57:58.554 - Script 'ServerScriptService.Scripts.Main', Line 11
16:57:58.554 - Stack End