[DBNETLIB][ConnectionOpen (Invalid Instance()).]Invalid connection Error when binding MSSQL database with plesk 10

Connection to a named instance of SQL server 2005/2008 should be made using the format
‘VirtualServer\Instancename’. if the IP address of a machine running a named SQL server instance
(ONE)is, you can connect to the named instance using\ONE for the servername.

To avoid a client app from using the above convention for a servername, a client  alias can be created using the client network utility. Client network utility  can be initiated by

Start->Programs ->Microsoft SQL Server->Client Network Utility

and you can create a Named Pipes or TCP/IP alias for your server and try connecting again.

Written by actsupp-r0cks