I installed pymol a few days ago from source. Everything went smothly, except for when I tried to save a png image.
I used the command: ">png image.png, 1920, ray"
This gives the following error:

PyMOL>png test.png, 1920, ray
Traceback (most recent call last):
  File "/usr/local/lib/python2.7/dist-packages/pymol/parser.py", line 254, in parse
  File "/usr/local/lib/python2.7/dist-packages/pymol/exporting.py", line 338, in png
    r = _self._png(str(filename),int(width),int(height),float(dpi),
ValueError: invalid literal for int() with base 10: 'ray'

I don't really know if this is a problem with my python libraries or with pymol. If I do ">ray" it works without a problem, as works ">png image.png, 1920"