AIX: Could not login using NIS Account?

Hi there,

I am new to AIX environment, when I set up NIS Client for an AIX 5.3 Machine to connect to a Linux NIS Master, everything seems to be okie:

/etc/passwd: +::0:0:::
/etc/group: +:
ps -ef | egrep "ypbind": /usr/lib/netsvc/yp/ypbind -ypsetme -ypsetme

I can get all account information from NIS Master using ypcat

When I was logging in using NIS account, the machine denied and here is what I got from the secure log:

"failed login attempt for UNKNOWN_USER from ..."

Other AIX 5.3 machines on the same domain works ok.

please give me some advices, thanks in advance