Problems with jingle

hi, I have the same problems. and i have tried all the ways that i found in the forum.for example,

setting Media Services, 2 ips in stun settings.

but all is failed. still have the error:

“Unable to negotiate session.This may be caused by firewall configuration problems.”

1\ i have checked that there is no local firewalls .

2\ i have tried Gtalk,It’'s all OK in my test enviroments.Gtalk also use jingle.

who can tell me how to solve the problems.thanks.