What is going on with Amazon FBA applications

I have been trying to apply to sell a product for a few weeks now and have been denied every time even though this product isn't a product where you need a letter or message from the brand owner you just need an invoice , more than 10 units and some other minor things which I have. I applied the first time and they said you need to use a different invoice so I changed that and then they said we need an invoice rom your supplier so I did that and sent it off and now they have come back with 'We have determined your not eligible' I really don't understand this I have given everything they have asked for, all the products are genuine bought from a very reputable supplier. Does anyone have any advice?