[mod_python] FieldStorage and POST?

Hi,
I can't make FieldStorage instance give me my POST arguments.
When I send my form data through GET, FieldStorage contains them. But when  
I use POST and then do:

req.write(util.FieldStorage(req).list[0].value)

Python tells me "list index out of range"
I have googled quite a lot and found bits of information about problems  
with POST and FieldStorage, but nothing that could help me figure out  
WHERE the POST data are.

Thanks in advance for every hint.

Dan