Contents of the log file:

ConTeXt ver: 2011.05.18 18:04 MKIV fmt: 2012.5.28 int: english/english

system          > cont-new.mkiv loaded
(C:/context/tex/texmf-context/tex/context/base/cont-new.mkiv
system          > beware: some patches loaded from cont-new.mkiv
)
system          > kk.top loaded
system          > options > begin of optionfile
system          > options >
system          > options > % runtime options files (command line driven)
system          > options > \unprotect
system          > options > % feedback and basic job control
system          > options > % handy for special styles
system          > options > \startluacode
system          > options > document = document or { }
system          > options > document.arguments={
system          > options > ["autopdf"]=true,
system          > options > }
system          > options > document.files={
system          > options > "kk.tex",
system          > options > }
system          > options > \stopluacode
system          > options > % process info
system          > options > \setupsystem[inputfile=kk.tex]
system          > options > \setupsystem[\c!n=1,\c!m=1]
system          > options > % modes
system          > options > % options (not that important)
system          > options > \startsetups *runtime:options
system          > options > \stopsetups
system          > options > % styles and modules
system          > options > \startsetups *runtime:modules
system          > options > \stopsetups
system          > options > % done
system          > options > \protect \endinput
system          > options >
system          > options > end of optionfile
(kk.top)
fonts           > latin modern fonts are not preloaded
languages       > language en is active
{C:/context/tex/texmf-context/fonts/map/pdftex/context/mkiv-base.map}
fonts           > preloading latin modern fonts (second stage)
(C:/context/tex/texmf-context/tex/context/base/type-siz.mkiv) (C:/context/tex/texmf-context/tex/context/base/type-otf.mkiv){C:/context/tex/texmf/fonts/map/dvips/lm/lm-math.map}{C:/context/tex/texmf/fonts/map/dvips/lm/lm-rm.map}
fonts           > virtual math > unable to resolve name mapsfromchar
fonts           > fallback modern rm 12pt is loaded
system          > begin file kk.tex at line 1
metapost        > initializing instance 'metafun' using format 'metafun'
metapost        > loading 'metafun.mp' (experimental metapost version two)
! terminal: >> picture
! Isolated expression.
<to be read again>
                   ;
<*> ...3u yscaled 60.09u shifted (69.85u,20.30u) ;
                                                   ;

system          > tex > error on line 17 in file kk.tex: terminal: >> picture
! Isolated expression.
<to be read again>
                   ;
<*> ...3u yscaled 60.09u shifted (69.85u,20.30u) ;
                                                   ;

7     numeric u;
8     u:=1;
9     textX:=87.51u;
10     textY:=96.31u;
11     pic:=thelabel.urt(btex {Test} etex scaled 1.00,(0,0));
12     draw pic shifted (textX, textY);
13     externalfigure "mill.png" xscaled 80.13u yscaled 60.09u shifted
14     (69.85u,20.30u) ;
15     \stopuseMPgraphic
16
17 >> \useMPgraphic{gh}
18
19     \stoptext
20

<inserted text> ...re.mp ; fi ; ;;;;]===], false)}

\processMPgraphic ...e ;\!!es , \MPaskedfigure )}}
                                                  \egroup \placeMPgraphic \d...
\handleuseMPgraphic ...hics \processMPgraphic {#3}
                                                  \endgroup
\douseMPgraphic ...{\@@MPG \currentMPgraphicname }
                                                  \empty \endMPgraphicgroup
<to be read again>

l.17 \useMPgraphic{gh}

?
! Emergency stop.

system > tex > error on line 17 in file kk.tex: Emergency stop ...

! ==> Fatal error occurred, no output PDF file produced!

I checked that I have

shell_escape.context = t
shell_escape_commands.context = mtxrun,luatools,texmfstart,texexec,mpost

in C:\context\tex\texmf\web2c\texmf.cnf

Please find attached the file log (kk.log).