I cannot connect an application using OLE DB

When I try to make the connection, the following message appears

"Cannot open database requested in login 'DBName'. Login fails."
Err Code = -2147467259

We are using SQL Server 2000 on NT Server 4.0 SP 6.
The client machine has MDAC 2.6 SP1.

All ideas are welcome.

ThanksSounds like the connection to the server has been made but the login cannot open the database. Could be because the database does not exist or because the login does not map to a valid user in the database.
Try just connecting to master.

i acn't login to a sql server with Database Engine Tuning Advisor

I'm trying to connect an instance (sql2005 standard edition) with the Database Engine Tuning Advisor (DETA), but it always fails.
I get this message:
"Failed to open a new connection.Failed to initialize MSDB database for tuning
(exit code: -1073741819).(DTAClient)"

The msdb database is exist on this server. What can i do?I compared the msdb database to an another db (where this feature is works) and I found some missing objects:
DTA% tables(22) and sp_DTA% store procedures(63)

I don't remember any option where I can set this objects (exist or not) and I didn't see any error when I installed this server.
?|||

This is most likely a security issue. The login account you are using from the tuning advisor doesn't have sufficient privileges to MSDB. The account you use for database tuning should have read/write access to msdb, because the DTA stores session information there (see BOL topic Considerations for Using Database Engine Tuning Advisor).