Some times if you select a Amazon category which requires pre-approval, following error will be returned by Amazon. You can see these errors in Selro -> Marketplace -> Update Status queue.

Seller is not authorized to list products in this category. For more details, see http://sellercentral.amazon.co.uk/gp/errorcode/8026

Following Amazon Categories required pre-approval from Amazon

Following link Amazon Seller Central gives full details.

https://sellercentral.amazon.com/gp/help/200333160/ref=sc_hp_200333160

For Amazon US sellers there is a specific form to submit to get the approval.

For Amazon UK customers, you can create a case as a starting point