Connection String... vb.net

The following code gives me an error: 40- could not open a connection to SQL Server.

Question: How can I handle this?
Imports System.Data.SqlClient
Imports System.Data.SqlClient.SqlCommand

Public Class Form1

    Private Sub Form1_Load(sender As Object, e As EventArgs) Handles MyBase.Load

        Dim cnn As SqlConnection = New SqlConnection

        Try
            Dim strCnn As String = "Server='Mike-Vaio';Database='NORTHWND.MDF';Trusted_Connection=True;"
            Dim cmd As SqlCommand = New SqlCommand("Select * From tblProduct", cnn)
            cnn.ConnectionString = strCnn
            cnn.Open()
            Dim dr As SqlDataReader = cmd.ExecuteReader

            If dr.HasRows Then
                MessageBox.Show("Has Records")
            Else
                MessageBox.Show("Has no Records")
            End If
            ' DataTable dt = new DataTable();
            'dt.Load(dr);
            'dataGridView1.DataSource = dt;
        Catch ex As Exception
            MessageBox.Show(ex.Message)
        Finally
            cnn.Close()
        End Try

    End Sub
End Class

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LVL 34
Mike EghtebasDatabase and Application DeveloperAsked:
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ste5anSenior DeveloperCommented:
This sounds like you're trying to load the NORTHWND database as user instance, but it is already active. Just open SSMS (SQL Server Management Studio) and take a look at the online databases.

Try a different connection string: Server=.\SQLEXPRESS12;Database=NORTHWND;Trusted_Connection=True;
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Mike EghtebasDatabase and Application DeveloperAuthor Commented:
Hi ste5an,

FYI, I have revised (changed and improved) my original question several times. My apology for this. I want just make sure you have read my latest version.

Mike
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Mike EghtebasDatabase and Application DeveloperAuthor Commented:
re:> and take a look at the online databases.

How do I do this?
0
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Mike EghtebasDatabase and Application DeveloperAuthor Commented:
Oh, under task 'Take Offline" shows enabled. This indicates it is already online.

BTW, I am using SQL Express 12 and vs2012

Also, I checked and found out the following:

SQL Server (SQLEXPRESS12)  is running
SQL Server Agent (SQLEXPRESS12)  is stopped
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Mike EghtebasDatabase and Application DeveloperAuthor Commented:
I was missinf SQLEXPRESS12 in:

Server='Mike-Vaio\SQLEXPRESS12';Database

Dim strCnn As String = "Server='Mike-Vaio';Database='NORTHWND.MDF';Trusted_Connection=True;"
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Mike EghtebasDatabase and Application DeveloperAuthor Commented:
I've requested that this question be closed as follows:

Accepted answer: 0 points for eghtebas's comment #a40362406
Assisted answer: 500 points for ste5an's comment #a40362293

for the following reason:

I was missinf SQLEXPRESS12 in:

Server='Mike-Vaio\SQLEXPRESS12';Database

Dim strCnn As String = "Server='Mike-Vaio';Database='NORTHWND.MDF';Trusted_Connection=True;"
0
ste5anSenior DeveloperCommented:
So my answer was correct. You should give the points.
0
Mike EghtebasDatabase and Application DeveloperAuthor Commented:
I thought I gave the points, apparently there was a mistake.

Sorry,

Mike
0
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