[NTG-context] \setupwhitespace[small]

Dear ConTeXtnicians I am trying to track down something which causes \setupwhitespace not to work as expected in my document. Minimal documents work correctly but my complex handbook document has been affected. What other commands might cause \setupwhitespace to malfunction. \setupwhitespace[small] does not appear to work. It seems to give the same result as medium. none gives none, 3pt does not give 3pt but instead prints 3pt as though it was text, big does give slightly bigger than medium but not as much as it should. TIA -- Nigel