attach Database Error -very URGENT

hi to all
I got a probelm with attaching the database. I hv Database Name called "ABC". it is working fine. (contain MDF,LDF files)

I got new BackFiles from CLient. They sent MDF and LDF Files. But i could't able to attach the database i got the following error while attaching the databse.

Server: Msg 5173, Level 16, State 2, Line 1
Cannot associate files with different databases.

I tried with the following query

EXEC sp_attach_db @.dbname = N'ABC',
@.filename1 = N'C:\DataBase\ABC.mdf',
@.filename2 = N'C:\DataBase\ABC_log.ldf'

i Tried with EnterPrise Manager also i got the same error. you can see the attachment file to view the ERROR.

Please Help me .Urgently...http://support.microsoft.com/default.aspx?scid=kb;EN-US;281122 to resolve the issue.