\set Staff.keySignature gives error "cannot find property type-check for `keySignature' (translation-type?)"

[Harald Christiansen]

Hi,

The last time I compiled a *.ly containing this snippet, it worked as expected:

\set Staff.keySignature = #`((5 . ,FLAT))

Now it gives me an error:

warning: cannot find property type-check for `keySignature' (translation-type?).  perhaps a typing error?

Using
\version "2.18.2"
and _no_ changes made to the *.ly file.

Now the _actual_ current version is 2.19.42

I am referring to this
http://lilypond.org/doc/v2.18/Documentation/snippets/pitches#pitches-non_002dtraditional-key-signatures

Any suggestions ?

Thank you.

Regards.

-- 
Nihil verus. Omnia possibilia.