NAT not workinig with WinGate 5.2.2

[rav]

First some facts about configuration:
server is win xp with two interfaces:
10.6.8.12 - Internet connection
172.16.3.20 - intranet connection
WinGate 5.2.2 is running, Extended Network Driver is enabled,
WinGate Firewall is disabled
DNS Service is enabled
no other firewall/NAT software is running
server can ping anyware with no problems
client is running Windows 2000 Prof with just one interface:
172.16.3.212 (gateway is set to 172.16.3.20 of course)
client can ping the server
client can use DNS

Problem:
client CANNOT ping outside the server :-( nor do any TCP/IP
connection (http, ssh etc)

When "ping 149.156.96.9 -n 10000" is running on client I can
observe in GateKeeper on server (on the Activity tab) that something
is going on "NAT: ICM 172.16.3.212 <-> 149.156.96.9". On the History
tab I can observe many records with "60" in Bytes In column and "0" in
Bytes Out column (always!).

What is wrong?