How do I get these update/delete functions for my database working?

Hello. I am very new to database programming (still learning the basics of it), so when I have read up on this issue elsewhere, I have not been able to use the information given to resolve this bug. In my program's update and delete functions, I am getting this class error message:

Concurrency violation: the UpdateCommand affected 0 of the expected 1 records.

It will happen if and only if the record that it's supposed to update/delete has been added to the database during that program's execution. I have read up on this problem and have gathered some information about it, but I really need to ask somebody to please show me a couple of lines through which to correct my code to resolve this error. After I see that, it will help me learn how to correct/avoid this error in the future, but please show me the actual code to correct this. Here is the code for the add, update, and delete functions:

Code:

---

        private void btnAdd_Click(object sender, EventArgs e)
        {
            con.Open();

            DataRow row = dataset.Tables["Contacts"].NewRow();
            row[1] = tbFirstName.Text;
            row[2] = tbMiddleName.Text;
            row[3] = tbLastName.Text;
            row[4] = tbSuffix.Text;
            row[5] = tbHomePhone.Text;
            row[6] = tbCellPhone.Text;
            row[7] = tbOtherPhone.Text;
            row[8] = tbStreetAddress.Text;
            row[9] = tbCityAndState.Text;
            row[10] = tbCountry.Text;
            row[11] = tbEmail.Text;
            currentRow = row;

            dataset.Tables["Contacts"].Rows.Add(row);
            dAdapter.Update(dataset, "Contacts");

            recordShown = true;

            con.Close();
        }

---

Code:

---

        private void btnUpdate_Click(object sender, EventArgs e)
        {
            if (recordShown)
            {
                con.Open();

                currentRow[1] = tbFirstName.Text;
                currentRow[2] = tbMiddleName.Text;
                currentRow[3] = tbLastName.Text;
                currentRow[4] = tbSuffix.Text;
                currentRow[5] = tbHomePhone.Text;
                currentRow[6] = tbCellPhone.Text;
                currentRow[7] = tbOtherPhone.Text;
                currentRow[8] = tbStreetAddress.Text;
                currentRow[9] = tbCityAndState.Text;
                currentRow[10] = tbCountry.Text;
                currentRow[11] = tbEmail.Text;

                SqlCommandBuilder updateBuilder;
                updateBuilder = new SqlCommandBuilder(dAdapter);
                dAdapter.Update(dataset, "Contacts");

                con.Close();
            }
            else
            {
                MessageBox.Show("Please locate/add a record first.");
            }
        }

---

Code:

---

        private void btnDelete_Click(object sender, EventArgs e)
        {
            con.Open();

            currentRow.Delete();
            dAdapter.Update(dataset, "Contacts");
            clearTextBoxes();
            recordShown = false;

            con.Close();
        }

---

Thanks!