makam.ly and Staff.keySignature

[Blöchl Bernhard]

I use makam.ly and found that
\key g \minor
does not work (no Glyph found ...)
Tried as a test
\set Staff.keySignature = #`(((0 . 6) . ,FLAT) ((0 . 5) . ,FLAT))
same result.
I tried an example from the reference as well

freygish = #`((0 . ,NATURAL) (1 . ,FLAT) (2 . ,NATURAL)
    (3 . ,NATURAL) (4 . ,NATURAL) (5 . ,FLAT) (6 . ,FLAT))

\key c \freygish

same negative result.

I use Farahfaza ( 
http://www.maqamworld.com/maqamat/nahawand.html#farahfaza ), that is a 
Nahawand transposed to g and compares to our g minor.

How can I get a key signature with makam.ly?

Thanks for any help and regards