I came across an issue in context (context ver. 2011.05.18 22:26, LuaTeX ver: beta-0.65.0-2010121421 (rev 4034) ) when trying to cite a bibliography item having an author with a German umlaut "ä"

Compiling the short example below, produces the following output and then 

-------------------------------------

...

system > begin file test.tex at line 3
publications > loading database from test.bbl
(test.bbl
! Undefined control sequence.
\@@pbs ->Tr\0
6
\dostartpublication ...@@pby \noexpand \or \@@pbs
\noexpand \or \@@pbn \noex...
l.9 \stoppublication

)
backend > xmp > using file 'M:/Programs/context/tex/texmf-local/tex/context/base/lpdf-pdx.xml'
pages > flushing realpage 1, userpage 1, subpage 1
system > end file test.tex at line 5

...

mtx-context | fatal error: return code: 1

----------------------

The strange thing is that when I change the Tr\"{a}ger to Schr\"{a}ger, everything works just fine.

Does anybody know what's going on here?!

Julian

---test.tex---------

\setuppublications[alternative=apa,sorttype=bbl]
\setupbibtex[database=test.bib]
\starttext
I'd like to cite \cite[Entry1].
\stoptext

-----test.bib:---this one produces an error-----

@misc{Entry1,
author = {Tr\"{a}ger, D},
title = {{Some Document}},
year = {2006}
}

----------------------

----test.bib--this works---

----------------------