C# MDF database is not inserting data even if success message is displayed

I need to insert data when user clicks. But, my code isn't doing it. Even though it displays the data inserted message, the data is not inserted. How can I find the mistake?

private void bunifuFlatButton2_Click(object sender, EventArgs e)
    {

        SqlConnection con = new SqlConnection(@"Data Source=(LocalDB)\MSSQLLocalDB;AttachDbFilename=**F:\Blackhat\Blackhat\Blackhat.mdf**;Integrated Security=True");
        try
         {
            con.Open();
            SqlCommand cmd = new SqlCommand("Insert Into Clients(name) VALUES ('"+clientname.Text+"')", con);
            cmd.ExecuteNonQuery();
            MessageBox.Show("Success "+clientname.Text);
             con.Close();
         }
         catch (SqlException ex)
         {
             MessageBox.Show("Failed"+ex);
         }
    }