Male dog won't breed

Just my 2 cents he might have the tools but they don't work and the reason I say this is because every fixed male I have hunted with gets humped by both males and females and when you said another dog was humping him that is what made me think that maybe he just dont have what it takes its these dogs have no testosterone so they smell different and dogs want to hunch on them I know your dog isn't fixed but he may have been born where he produces no testosterone and is sterile not sayin that is what it is but you might get him tested