ISA 2000 & CheckPoint VPN-1 SecureRemote problem

hello

i try to connect to the network of our customers, whom have checkpoint fire wall through CheckPoint VPN-1 SecureRemote NGX R55 & R60.

the connection try fails with the following error:

"Checking network connectivity...
Preparing connection...
Connecting to gateway...
Gateway not responding
Connection failed"

i've checked isa 2000 for the following port, which applies to checkpoint remotesecure:

4443 (tcp) outbound - allow always to all domain users
500 (tcp) outbound inbound - allow always to all domain users
2746 (udp) outbound - allow always to all domain users
500 (udp) send receive - allow always to any request
500 (udp) receive send - allow always to any request
4500 (udp) send receive - allow always to any request
18232 (udp) receive send - allow always to any request
18232 (tcp) outbound - allow always to any request

anyone have any idea about how to solve this problem? do you know this issue?

thank you all