[OS X] can't connect to db

[rdack]

using pygresql-3.2, postgresql-7.1.3, mac os x 10.1, mac g4.
	doesn't work:
db = _pq.connect('rda')

my python file is in '/Library/WebServer/CGI-Executables'
in that directory i can do 'psql 'rda'' ok, but running the .py file
throws an exception in connect.

i also tried 
db = _pq.connect('rda',None,-1,None,None,'bobacker')
and:
db = _pq.connect('rda',None,-1,None,None,'postgres')
and for coming in from browser html file:
db = _pq.connect('rda',None,-1,None,None,'www')
'postgres',  'bobacker', and 'www' are postgresql users.

what can i do?