this.getConfig().getBoolean("Items.35.tradabl

Why do I get "false" for id 35 using following code? this.getConfig().getBoolean("Items."+I.getTypeId()+".tradable")

config.yml:
# default config.yml
PurchasePriceMultiplier: 1.1
InitPriceFactor: 7
Items:
  - 33:
    tradable: true
  - 35:
    tradable: true
  - 37:
    tradable: true