GTIN exemption and valid PTD

Hey,

I’m trying to apply for a GTIN exemption as I am the manufacturer of my products (stickers) and I don’t want to spend money on UPCs.

I also don’t want to use “Generic”.

I’ve been reject with the following reason “the provided PTD is not valid.” I’ve asked what is a PTD and they say product type definition. Has anyone encounter this problem before. What should I do next?