If you remove the space, i.e.

\starttext
\startchapter
[ title={Vorwort}, reference=chap:vorwort]

Siehe \in{Kapitel}[chap:neu] \at{Seite}[chap:neu].
\stopchapter
\startchapter
[ title={Neu}, reference=chap:neu]

Bla.
\stopchapter
\stoptext

it works here.

/Mikael


On Sat, Nov 2, 2013 at 1:49 PM, Wolfgang Werners-Lucchini <wwl@musensturm.de
> wrote:

> Hallo,
>
> I must do someting wrong
> ---
> \starttext
> \startchapter
> [ title={Vorwort}, reference=chap:vorwort ]
>
> Siehe \in{Kapitel}[chap:neu] \at{Seite}[chap:neu].
> \stopchapter
> \startchapter
> [ title={Neu}, reference=chap:neu ]
>
> Bla.
> \stopchapter
> \stoptext
> ---
> I get an error: unknown reference '[][chap:neu]'
>
> Wolfgang
>
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