[NTG-context] \loadcurrentMPgraphic from metafun manual

Hi, I have tried the following example (metafun-p.pdf, p. 112-3): \startMPgraphic draw unitsquare xscaled 5cm yscaled 1cm withpen pencircle scaled 2mm withcolor .625red; \stopMPgraphic \hbox \bgroup \loadcurrentMPgraphic{width=5cm,height=1cm}\placeMPgraphic \quad \loadcurrentMPgraphic{width=8cm,height=1cm}\placeMPgraphic \egroup but nothing is drawn unless I remove the setups in curly braces (in which case a rectangle 5cm x 1cm is drawn). Is there a different way to pass options to the figure inclusion macro? Nicola