When you say neonate, how young was it? Was it eating from the previous owner? I think if you can rule out that it is not a mistake on your part, then you may have indeed bought an animal that probably shouldn't have been sold. You can pursue this any which way you would like; if you want to give it your all, then the perhaps a vet is the next option. I know a number of breeders euthanize offspring that never take to feeding on their own. I cannot fault them for this, as certainly there is always a percentage of offspring that don't have what it takes to flourish.

Ian