Traffic flow question

I use next example scheme:

netflow-collector <- RB5/AP (ap1) <- wlan -> RB5/AP (base1) <- wlan -> RB5/AP (ap2)
                                                   \
                                                    `ether-> RB5/AP (base2) <- wlan -> RB5/AP (ap3)

On and enabled “Trafic Flow” v.5 which send flow on collector with settings:

                enabled: yes
             interfaces: all
          cache-entries: 1k
    active-flow-timeout: 1m
  inactive-flow-timeout: 5s

So, if I send or recieve files on/from client behind to client behind all ok. All numeric correct.
But, if I send/recieve from/on sombody from to client on - I see abrakadabra. Or just 0Rx/0Tx byte.
When my mistake?
How correct setup interfaces in trafic flow settings?