Scripts

Please help. Why does this script

garrisons={'G1', 'G2', 'G3', 'G4', 'G5', 'G6', 'G7', 'G8', 'G9'}
for j, gar in garrisons do
	Trigger(5, gar, 'capture_gar')
	garrisons[gar] = {}
	for i = 0, 6 do
		local t, n = GetObjectArmySlotCreature(gar, i)
		garrisons[gar]= {t, n}
	end
end

function capture_gar(oldowner, newowner, hero, gar)
	for i = 0, 6 do
		if garrisons[gar][1] ~= 0 then
			AddObjectCreatures(gar, garrisons[gar][1], garrisons[gar][2]*2)
		end
	end
	DenyGarrisonCreaturesTakeAway(gar, 1)
	Trigger(5, gar, nil)
end

produce this error: invalid parameter type: object name must be string?