unable to create PDF through pyylons

[Anil]

I have a simple piece of code that works when I do this through
command line. (e.g. save to a test.py and then run it through cli).

pdf = pisa.CreatePDF(
html,
file(filename, "wb"))

However, when I do the same thing in Pylons web framework, a blank/
empty PDF file is generated:

def test(self):
import ho.pisa as pisa2

pisa2.showLogging()
filename = "file.pdf"
html = """
<center>
<font size="30">Testing</font>
</center>
"""

pdf = pisa2.CreatePDF(
html,
file(filename, "wb"))
if pdf.err:
return pdf.err

return "OK"


Any idea?