bug with calt?

[ousia]

Hi Khaled,

I'm using fontspec (from TL2011 as updated today).

If I don't get it wrong from the documentation, fontspec supports the
OpenType feature calt in LuaLaTeX. For some strange reason, the
following sample doesn't work:

\documentclass{minimal}
\usepackage{fontspec}
\setmainfont[RawFeature={+calt,+ss11}]{Theano Didot}
\begin{document}
ββ θθ
\end{document}

Theano Didot contextual alternates enable different glyphs for initial
and medial/final beta (stylistic set 11 enables different glyphs for
initial and medial/final theta). Theano Didot is available at
http://thessalonica.org.ru/en/fonts-download.html.

Am I doing something wrong, is it a bug or an unimplemented feature?

Many thanks for your help,

Pablo