golang 和 ListenAndServeTLS 返回错误

Question

func main(){

    runtime.GOMAXPROCS(runtime.NumCPU())

    r := mux.NewRouter()

    www := r.Host("secure.domain.com").Subrouter()

    www.HandleFunc("/", Handler_www)

    api := r.Host("api.domain.com").Subrouter()

    api.HandleFunc("/", Handler_api)

    go func(){

        cert := "/var/ini/ssl/secure.domain.com/intermediate.crt"

        prv_key := "/var/ini/ssl/secure.domain.com/private.key"

        err := http.ListenAndServeTLS(":9443", cert, prv_key, r)

        if err != nil {

            log.Fatal("HTTPS server: ", err)

        }

    }

    err := http.ListenAndServe(":9000", r)

    if err != nil {

        log.Fatal("HTTP server: ", err)

    }

}