ORA-12638: Credential retrieval failed

hi members ,
we r having two database in two location loc1 and loc2. In both the place oracle 9.0.1 is running under win2k.

loc1
-------
Global_name = 'abc.abc.com'
Machine name =abc.com
loc2
Global_name = 'def.def.com'
Machine name =def.com

i have created the database link as follows
in loc1
*******
create public database link def.def.com using 'def.def.com'

in loc2
*******
create public database link abc.abc.com using 'abc.abc.com'

when i am trying from loc1
select * from dual@def.def.com i am getting the following error
ERROR at line 1:
ORA-12638: Credential retrieval failed

when i am trying from loc2
select * from dual@abc.abc.com i am getting the following error
ERROR at line 1:
ORA-12541: TNS:no listener

where as i am having one more database oracle 8i under win2k in another location. when i am trying the same i am getting the result..

please help me to solve this problem
thanks in advance
sudheesh

1.check the sqlnet.ora file from the pc u aer are trying to connect and make

sqlnet.authentication_services =none or comment out the whole line.

2. check the listener at the remote server to which u are trying to connect whether it is up and running.