LocalDB in Visual Studio 2015 - SQL manipulation of database

I have a form, with 2 textboxes and a button
The button calls InsButton_Click
Idea is to insert data if name is not there, otherwise update the row if it is.
Never got longer than testing, as the thinge can not find the table, when the program is running....

private void InsButton_Click(object sender, EventArgs e) // Skal indsætte data i databasen
{
String Navn = navnBox.Text;
String Relation = relationBox.Text;
String dbpath = "C:\\ZZ Mine Data\\MineC#\\Familie\\Familie\\Familie\\Familie.mdf";
StatusLabel.Text = "Arbejder";
if ((Navn.Length > 0) && (Relation.Length > 0))
{
SqlConnection conn = new SqlConnection("Data Source=(LocalDB)\\MSSQLLocalDB;AttachDbFilename=" + dbpath + ";Integrated Security=True;Connect Timeout=30");
conn.Open();
if (IsInData(Navn, conn) > -1)
{ // Opdaterer rækken
StatusLabel.Text = Navn + " findes allerede";
}
else
{ // Indsætter ny række
StatusLabel.Text = Navn + " findes ikke";
}
conn.Close();
}
}

private int IsInData(String navn, SqlConnection conn)
{
int idx = -1;
SqlCommand cmd = new SqlCommand();
SqlDataReader reader;

cmd.CommandText = "SELECT id FROM myfamily WHERE navn='" + navn +"'";
cmd.CommandType = CommandType.Text;
cmd.Connection = conn;

reader = cmd.ExecuteReader();
idx = (reader.HasRows) ? (int)reader.GetValue(0) : -1; // Data is accessible through the DataReader object here.
return idx;

}