TMG 2010 rules are not properly working

Hi all

I use TMG 2010 sp2, i created a rule access name is ""allow all" 

Protocol: all outbound traffic

From: Localhost, Internal

To: External, Internal

Condition: All Users

and Default rule Deny all

Result:

Success: My client can access internet via http, https, check mail via pop3 (port 110), smtp (port 25), access DNS server

Unsuccess: TMG machine can ping to clients, but clients can't ping to TMG

Clients  can't remote to TMG, external network but internal network is OK

TMG can't remote external network, sometime TMG can remote to internal network.

Have anyone else seen this kind of behavior? Thank you for you answers.

Mrk chuoicanai.