aunclfamily and fontspec

Hello,
having searched for an answer of my question, but have found no hints: I want to realize a critical edition for which I want to set some letters in the Artificial Uncial. I use lualtex and fontspec, but get this below. How can I solve this?
kind regards
Jens
=====
! LaTeX Error: Encoding scheme `B1' unknown.
See the LaTeX manual or LaTeX Companion for explanation.
Type  H <return>  for immediate help.
  ...
l.16 {\aunclfamily
                  AAGG}
?
LaTeX Font Warning: Font shape `TU/auncl/m/n' undefined
(Font)              using `TU/lmr/m/n' instead on input line 16.
MWE:
\documentclass{scrbook}
\usepackage{fontspec}
\setmainfont{oldstandard}
\usepackage{auncial}
\begin{document}
some text
{\aunclfamily AAGG}
some text
\end{document}
--
PGP-Key available
8923 F718 CFC1 9490 6711 0D3B 17A5 0634 6B71 A0DF