[PyFeyn] Installation error

[jhyu]

Hello PyFeyn developer,

I spent whole afternoon to install pyfeyn, but I failed. Here is the error message:

python pyfeyn_ss.py 
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You don't have PyX - that's a problem unless you're just running the setup script.
We try to finish the dvi due to an unhandled tex error
Traceback (most recent call last):
  File "pyfeyn_ss.py", line 15, in <module>
    fd.draw("pyfeyntest4.pdf")
  File "/Library/Python/2.7/site-packages/pyfeyn/diagrams.py", line 69, in draw
    c = self.drawToCanvas()
  File "/Library/Python/2.7/site-packages/pyfeyn/diagrams.py", line 61, in drawToCanvas
    obj.draw(self.currentCanvas)
  File "/Library/Python/2.7/site-packages/pyfeyn/lines.py", line 384, in draw
    l.draw(canvas)
  File "/Library/Python/2.7/site-packages/pyfeyn/deco.py", line 301, in draw
    t = pyx.text.defaulttexrunner.text(x, y, self.text, textattrs)
  File "/Library/Python/2.7/site-packages/pyx/text.py", line 1201, in text
    raise e
pyx.text.TexResultError: unhandled TeX response (might be an error)
The expression passed to TeX was:
  \ProcessPyXBox{\normalsize{}\setbox0\hbox{$\vcenter{\vrule width0pt}$}\PyXDimenVShift=\ht0\setbox0\hbox{{\gdef\PyXBoxHAlign{0.50000}\gdef\PyXFlushHAlign{0.50000}\PyXragged{}\PHiggs}}\lower\PyXDimenVShift\box0%
  }{1}%
  \PyXInput{5}%
After parsing the return message from TeX, the following was left:
  *
  *! Undefined control sequence.
  <argument> ...Align {0.50000}\PyXragged {}\PHiggs 
                                                    }}\lower \PyXDimenVShift \...
  <*> }{1}
  (cut after 5 lines, increase errordebug for more output)

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I am using Mac OSX 10.8.2 with Xcode 4.5.2. 
Python version 2.7.2, PyX version 0.12.1, PyFeyn version 0.3.3

I already put the python Path to 
export PYTHONPATH=/Library/Python/2.7/site-packages:$PYTHONPATH
so it should be able to recognize PyX.
According to the error message, it should be related to TeX. I installed MacTeX. 

 Could you help me out? Thanks very much! 

Best,
JIang-Hao Yu