[NTG-context] \mapsto + SimpleSlides

Dear all, I don't get \mapsto to display using SimpleSlides and MkIV. It shows in "normal" MkIV documents, and works in MKII Example below. Thanks for any advice. Matthias \usemodule[simpleslides] [style=BottomSquares, color=blue] \starttext \SlideTitle{Help!} \startformula \text{Mk II}\mapsto \text{Mk IV} \stopformula \stoptext