1: Do you have route configured to point the traffic to the tunnel interface? other routes are in place?
2: 'get event' should show the vpn related event, whether device tried to initiate IKE packets or not etc.
3: Check the KB https://kb.juniper.net/InfoCenter/index?page=content&id=KB14330&actp=search about how to set up S2S based VPN.
4: If everything is in place then monitor should force device to initiate the IKE packets.
Thanks,
Vikas