VPN up but still can’t ping!

Here’s my scenario:
Mesh VPN, 2 ISP’s using Fiberlogic appliance

HQ –vpn– Tampa Data Center
HQ –vpn– Chicago Office

If I open a Ping session, I can ping some internal addresses in Tampa and Chicago but they time out after a while. Meanwhile, to confuse things a bit more, I can ping from Tampa to HQ with no problem.

I’ve been breaking my head and ran out of ideas. It seems like a VPN issue but I have checked the logs and even contacted support and they found nothing. Clearly the VPN is UP if I can ping from Tampa to HQ and Chicago.

Please anyone with any ideas please shout!

Thanks,
D