Shirt Script Not Working

Part of my script were Im trying to make it pick a random shirt id from the list isnt working. Whenever I go in game the shirt just ends up being blank on the dummy.
Here Is My Code.

shirts = {13059372422, 13059372422, 13059372422, 13059372422, 13059372422}

local randomshirt = math.random(1,#shirts)
local clothing = script.Parent

clothing.ShirtTemplate = '' ..shirts[randomshirt]

When setting the shirt of a humanoid, you don’t use the shirt ID you find on the catalog. To convert it, make a dummy and paste the shirt id in. Then grab the new id at the end.