Many had trouble with btex etex including myself. A possible answer 
you might find in the appended context source file. You need a rather 
recent version context and a small handcrafted file by Hans as given 
in the text. It is rather wordy and not written for experts, but 
search for \forceMPTEXgraphictrue and you are in the neigbourhood. 
HGr...Karel.

On 9 Nov 2002, at 14:57, Micha  Morawski wrote:

> I have tried to repeat the example in the file "Creating metapost examples"
> (mmakempy.pdf) and I receive result as below and empty place in my document.
> Can anyone give me a hint?
> 
> This is MetaPost, Version 0.641 (Web2c 7.3.7x) (mem=metafun 2002.10.31)  31
> OCT 2002 22:25
> **&metafun mpgraph
> (mpgraph.mp
> {randomseed:=3603}
>  (d:/TeXLive/texmf/metapost/base/graph.mp
> (d:/TeXLive/texmf/metapost/base/format.mp
> (d:/TeXLive/texmf/metapost/base/string.mp)
> (d:/TeXLive/texmf/metapost/base/texnum.mp
> >> d:/TeXLive/texmf/metapost/base/texnum.mp
> >> texnum.mpx
> ! Unable to make mpx file.
> l.14 init_numbers(btex
>                       $-$etex, btex$1$etex, btex${\times}10$etex,
> The two files given above are one of your source files
> and an auxiliary file I need to read to find out what your
> btex..etex blocks mean. If you don't know why I had trouble,
> try running it manually through MPto -tex, TeX, and DVItoMP.
> 
> 
> Thanks in advance
> Michal
> 
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