accounting file with belkin 54g wireless router

Hi all, I have set up the freeraiuds to authenticate the user using WPA TKIP authentication method. The router I use is belkin 54g wireless router. I am able to authenticate the user correctly and the auth log file records all activities, but I am not able to get the accounting file. I rememeber a while back when I browsing this thread, someone mentioned that no every router sends accounting data to radius. Is this right? If so, what are the router sent acct data? If no, what do I need to do to get the acct data? Thanks a lot! Michael