insertion failed in database

i am trying to insert into database,  The problem is  insertion data not save in my DataBase1.mdf i dont know why?
When my program is running, the first time that I insert data, they show in gridView1 but not store in database1.mdf
anyone help me
DB name : inventry
table name: addProduct
column : pid,title,descrtion,type,vendor,price,isbn
full project is attached
 


Button code file

private void button1_Click(object sender, EventArgs e) { String con = ConfigurationManager.ConnectionStrings["inven"].ConnectionString;   SqlConnection connection = new SqlConnection(con);   connection.Open(); SqlCommand cmd = new SqlCommand("Insert into addProduct(title,descrtion,type,vendor,price,isbn) values(@title,@descrtion,@type,@vendor,@price,@isbn)", connection);   cmd.Parameters.AddWithValue("@title", textBox1.Text); cmd.Parameters.AddWithValue("@descrtion", textBox2.Text); cmd.Parameters.AddWithValue("@type", textBox3.Text); cmd.Parameters.AddWithValue("@vendor", textBox4.Text); cmd.Parameters.AddWithValue("@price", textBox5.Text); cmd.Parameters.AddWithValue("@isbn", textBox6.Text);   int rows = cmd.ExecuteNonQuery(); if (rows != 0) { MessageBox.Show("Inserted"); } else { MessageBox.Show("Insertion failure"); } connection.Close(); }