[NTG-context] Where is error in my code?

I edit 1 file metafun follow: \startMPenvironment \usetypescript[times][texnansi] \switchtobodyfont[times,10pt] \stopMPenvironment \startMPpage fill fullcircle scaled 2cm withcolor red; label(\sometxt{Cn},origin) withcolor white; \stopMPpage