I have a VB2008 program accessing a Database. It's been working ok on SQL Server 2008 R2 Express using:
Code:
    Private Sub frmLogon_Load(ByVal sender As Object, ByVal e As System.EventArgs) Handles Me.Load
        AppName = My.Settings.AppTitle
        Me.Text = AppName + " - Logon"
        Try
            SQLcon.ConnectionString = "Server=.\SQLEXPRESS; Initial Catalog=EPOD; Integrated Security=SSPI;"
            SQLcon.Open()
        Catch ex As Exception
            MsgBox("Unable to Connect to EPOD Maintenance Database " + ex.Message, , AppName)
        End Try
    End Sub
Having attached the Database to SQL Server 2012 Express, it fails to connect, the error being displayed is:
"Unable to Connect to EPOD Maintenance Database A network-related or instance-specific error occurred while establishing a connection to SQL Server. The server was not found or was not accessible. Verify that the instance name is correct and that SQL Server is configured to allow remote connections. (provider: SQL Network Interfaces, error 26 - Error Locating Server/Instance Specified)"

If I use VB6:
Code:
Private Sub Form_Load()
Dim dbUser As String
Dim dbPassword As String
Dim dbName As String
Dim dbServer As String
Set db = New ADODB.Connection
dbName = "epod"
dbServer = ".\SQLEXPRESS"
db.ConnectionString = "Provider = SQLNCLI11;Data Source=" & dbServer & ";Initial Catalog=" & dbName & ";Integrated Security = SSPI"
db.Open
End Sub
the connection is fine.

Any ideas ?