Parent ASIN cannot be fulfilled by Amazon

There are some things that Amazon will not allow to be fulfilled by them. Some of them are really silly. eg I can sell an Airfix Spitfire Model Kit via FBA. No problem. However, I cannot sell the special edition Airfix Spitfire Model Kit via FBA cos it comes with little pots of paint and glue. These things are required to build the model kit but not to be INCLUDED with the model kit. I can sell any of it FBM. Without knowing your product it’s not possible to say for sure, but I suspect it may be a similar case