Error Creating Linked Server To Excel

Hi,
Please help, I'm getting desperate. Any ideas warmly welcomed!
I'm trying to read from a basic excel file (1000 or so rows from
column A) but am having problems. The code I am using is:

Declare @Return Int
SET NOCOUNT ON

Exec @Return= [master]..[sp_addlinkedServer] 'READ_XLS', 'EXCEL',
'Microsoft.Jet.OleDB.4.0' , 'e:jsbackupRACodes.xls',
NULL, 'EXCEL 8.0'
print 'set up Return : ' + convert(varchar(10),@Return)
--NB E: is the drive as seen oon the server

EXEC sp_addlinkedsrvlogin
@rmtsrvname = 'READ_XLS',
@useself = 'true'
print 'login Return : ' + convert(varchar(10),@Return)


When I try to read from the (one) excel sheet in the file, via
Select * from [READ_XLS]...RACodes$
or to list what tables/sheets are available, via
exec sp_tables_ex 'READ_XLS'

I get the following error:

OLE DB provider 'Microsoft.Jet.OLEDB.4.0' reported an error.
Authentication failed.
[OLE/DB provider returned message: Cannot start your application. The
workgroup information file is missing or opened exclusively by another
user.]
OLE DB error trace [OLE/DB Provider 'Microsoft.Jet.OLEDB.4.0'
IDBInitialize::Initialize returned 0x80040e4d: Authentication
failed.].

What am I missing?

*Many* thanks in advance.
Andy