Lost package after use FreeRadius

Dear Freeradius, At first, I use RouterOS(Mikrotik) as pppoe server and radius server. Now I use RouterOS as pppoe server and user FreeRadius as radius server. After changing as above, we find some pppoe users can dial up successfully via freeradius, but their internet transportation will lost package even can’t visit any website. I would like to know, how to explain the situation? What am I supposed to solve this problem? P.S When I change RouterOS to pppoe and radius server again (disable freeradius), it will all be ok. Thank you very much. Robin Lu