error 5886 while adding generic product

I am trying to add a generic product. it shows me an error stating

" you are attempting to contribute to this restricted generic ASIN by trying to change its detail page or create and update an offer. You must create a new ASIN by following the process outlined in our Add a Product tool to be able to make changes such as extending this ASIN to a new store, creating a new variation relationship, updating ASIN attributes, or adding offers to sell the product. If you are using inventory file templates, provide the Batch ID of the inventory file process report."

I opened a case with Amazon and sent them a real-time photo of the product in my hand but they say it is error 5886

I can't understand that if a product is generic and I have a product in my hand then why restriction ? although the product is not branded and other seller is selling why i am unable to sell ?

I want help in this matter.