Nanostation problem

Sorry for my bad english.I have routerboard RB450G.Get internet from ISP by pppoe on WAN - port 1.Port 2,3,4 and 5 is bridge.After bridge i have Nanostation 2.On Nanostation 2 i have 5-6 clients with laptops.Internet on this laptops is perfect,but from RB450G to Nanostation dont have ping.Dont have ping from Nanostation to RB450G.Where is problem?

check your arp table

/ip arp print

This command say - Nanostation MAC address is not in ARP table.But i add this MAC in ARP table.Where the problem?Help me.