You said that you tried the "CreateItem:" cheat? Did you try both codes, KEY12 and KEY13? I think that KEY12 is the correct one, but I'm not positive.
Also, be sure to check the inventory of *all* your party members. If you have one of your NPCs selected when you use the CreateItem cheat, it will spawn the item with that NPC.
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Now where did I leave that doughnut?!