enterprisedb package and pam on debian

Hiho,

I'm running the package 9.0.7 from enterprisedb and have some problems
getting the pam module to work on debian.

pam basically works - i just configured a more secure password policy.

the enterprisedb package has pam support included. at least i see with ldd
that i knows the pam library.

the postgres service is named postgres so i created a file
/etc/pam.d/postgres and added the lines

auth required pam_stack.so service=system-auth
account required pam_stack.so service=system-auth

i found in another mail thread.
I also tried to copy files from other predefined services like sudo or
login.

the error is always:
root:/etc/pam.d# psql -U testuser postgres
psql.bin: FATAL: PAM authentication failed for user "testuser"

the line in pg_hba.conf is
# TYPE DATABASE USER CIDR-ADDRESS METHOD
local postgres testuser
pam

any idea what's wrong here?
or does anybody have a good how-to?

thanks,
Uwe