[NTG-context] extracting pages using luacode

I'm trying to extract pages from an existing pdf using lua. But this approach to extract pages 11 and 30 does not work: \starttext \startluacode for i, blz in ipairs({11, 30}) do context.startTEXpage() context.externalfigure("my_pdf.pdf", page=blz) context.stopTEXpage() end \stopluacode \stoptext Where am I missing the point? .F