error trying to change transparency with a GetChildren() value?

wait(2)

local children = script.Parent:GetChildren()

for i = 1, #children do
allstuff1 = children[i]
	allstuff1.Transparency = 0.7
end
wait(0.1)
for i = 1, #children do
allstuff1 = children[i]
	allstuff1.Transparency = 0.6
end
wait(0.1)
for i = 1, #children do
allstuff1 = children[i]
	allstuff1.Transparency = 0.4
end
wait(0.1)
for i = 1, #children do
allstuff1 = children[i]
	allstuff1.Transparency = 0.1
end

im trying to change a group of parts transparency in stages, Im getting an error at line 7 saying: (transparency is not a valid member of script)

You need to add a check.

for i = 1, #children do
if not i:IsA("Part") then return end--It checks if the object is a part and if not then it stops the current loop
allstuff1 = children[i]
allstuff1.Transparency = 0.7
end