Problems VPN IPsec without communication

Hi!

I create a VPN IPsec between 2 Fortinet firewall:

1 FG500E (Firmware v6.0.4 build0231 (GA))

2 FG60E  (Firmware v5.6.8 build1672 (GA))

The tunnel established OK, but I can't see traffic into the tunnel comunicacion.

I see the traffic leaving my FW FG500E, the FG60E receives it and answers it, but that answer is no longer received by the FW500E.

As reference in the FG60E an ISP in the WAN1 existed and a new ISP was added in the WAN2.

At the beginning, the tunnel worked using WAN1, then it was only with the WAN2 provider, and since that change the tunnel no longer worked.

Please help me!