Cisco 5505 VPN interface not pingable

Hi,

It's been a long long time that I haven't touch a PIX or ASA appliance, and I'm very very rusty.

I just bought a Cisco 5505, did setup some stuff in there nothing to fancy. But I have trouble with this:

The IP of my internal LAN is 192.168.56.1 I have a VPN tunnel open between site X and this 5505 (site Y), this VPN tunnel is created between 2 on my internal LAN (X: 192.168.18.1 and Y: 192.168.56.1) I have also a Cisco 2960 POE switch (192.168.56.19)

When I'm on my network site Y (192.168.56.0/24) I can ping/telnet

192.168.56.1 (5505) and 192.168.56.19 (switch)

When I'm on my network site X (192.168.18.0/24) I can NOT ping/telnet

192.168.56.1 (5505) but I can ping/telnet 192.168.56.19

What I'm missing ? I'm sure it is a single thing.

Thanks for your help