must define username in radius client???

[saeedeh motlagh]

hello guys,
i wanna have authentication via radius server.  in my local network,
one system is radius server and the others are clients. the server is
running well. when a client login, it sends an access-request to the
server. if the user name and password are defined in the server, the
server sends back the access-accept to client. if the user name is
defined in the client, the login is successful but if this user name
is not defined in the client, the login failed and say "login
incorrect" although the client receives access-accept from the server.
i wanna know if there is any way to have authentication successfully
without defining any user name in the client system?
yours,