Hi, I've been here for a whopping two days and am trying my best to figure out all the UI functions on my own (or reading the wiki)…

Yesterday I bred my mares to some available studs to get the hang of the whole breeding mechanic on here, and one of my foals is stuck in transit? I keep trying to “board at home” but it repeatedly says “successfully moved 0 horses…”. I didn't have this problem with the other three foals I had, and I'm positive I still have stall spaces available for him to be moved into. Help?