[NTG-context] Bibliography in luatex: another question

Hi all, I encounter a strange behaviour with luatex: An entry of my bib file has this author's name: author = {Antoine {Destutt de Tracy}}, I enclose the complex name with {} to avoid confusion with the first name, as is usual with bibtex. But with a "\cite[author][destv]" command, the result in the pdf is: (Des- tutt de Tra- cy) which never happened with pdftex or xetex. Any idea? -- Jean