[NTG-context] getmarking and empty chapter number

Hi all, I'm just trying to wrap my mind around why the following doesn't work as I expect: -- \setupheadertexts [] [{\doifsomething{\getmarking[sectionnumber]}{\getmarking[sectionnumber]\enskip}\getmarking[section]}] [{\doifsomething{\getmarking[chapternumber]}{\getmarking[chapternumber]\enskip}\getmarking[chapter]}] [] -- When this encounters an unnumbered \startchapter (say in the front matter) then this \doifsomething should detect this void and in particular not insert the \enskip. For some reason the space ends up in the PDF nevertheless :-( Any ideas? Many thanks, Oliver