mathtext and postscript backend

Hello,

I have a problem to obtain a good ps file (with mathematical symbol) with matplotlib. That's work very good with a png file but not with a postscript.

I tried to define the TTFPATH and AFMPATH but that change nothing. I think that I miss one configuration somewhere but I can't arrive to find what...

Thank you for this soft, I just begin to use but it's seems very interesting

    Nicolas