[NTG-context] white color turns black inside a table

Hello, I have problems with the following minimal example (I only want to typeset white labels inside the table), but maybe I'm the only one again: \setupcolors[state=start] \starttext \startcolor[white] \placetable[force]{none}{\starttable[|r|] \NC \color[red]{me} \AR \stoptable} \placetable[force]{none}{\def\a#1{\color[white]{#1}}\starttable[|r|l|] \NC \a{one} \NC \a{one} \AR \NC \a{two} \NC \a{two} \AR \stoptable} \placetable[force]{none}{\starttable[|r|] \NC \color[white]{me} \AR \stoptable} \stopcolor \stoptext I get black labels instead of white ones in the second and third table. Any idea what goes wrong? I'm using mkii. Mojca