Route thru L2TP IPSEC

Hello every body, i have a question :
I have succeded to crate L2TP ipsec tunnel from a peplink 30 toward mikrotik, but adding static route on the peplink to the mikroitk seems to not work .

My topo is :
LAN A --PEPLINK ---- WAN (L2TPIPSEC) ---- Mikrotik Router - LAN B & LAN C
Let say my L2TP ipsec vpn gave me remote IP and local IP
When i get to the peplink and i add route like :
LAN B Subnet (ex: - GW:
It doesnt work, the peplink doesnt forward packet from LAN A to LAN B

did i forgot something
Thank you