The INSERT statement conflicted with the FOREIGN KEY constraint "FK_Auto_Part_Details_Auto_Parts". The conflict occurred in database "WhiteWhaleDB", table "dbo.Auto_Parts", column 'Job_Card'.

private void btn_Add_Click(object sender, EventArgs e)
        {
           for (int i = 0; i < dgv_Add_job_card.Rows.Count ; i++)
                        {
                            con.Open();
                            s = "insert into Auto_Part_Details (Items_No, Job_Card, Value_Part, Auto_Parts_id, Repair_id, New_Old_Part, Provider_id, Installation_id, Notes) values (@Items_No, @Job_Card, @Value_Part,@Auto_Parts_id , @Repair_id,@New_Old_Part , @Provider_id, @Installation_id , @Notes)";
                            sd=new SqlCommand(s,con);
                            sd.Parameters.AddWithValue("@Items_No", dgv_Add_job_card.Rows[i].Cells[0].Value);
                            sd.Parameters.AddWithValue("@Job_Card", dgv_Add_job_card.Rows[i].Cells[1].Value);
                            sd.Parameters.AddWithValue("@Value_Part", dgv_Add_job_card.Rows[i].Cells[2].Value);
                            sd.Parameters.AddWithValue("@New_Old_Part", dgv_Add_job_card.Rows[i].Cells[5].Value);
                            sd.Parameters.AddWithValue("@Notes", dgv_Add_job_card.Rows[i].Cells[7].Value);
                            sd.Parameters.AddWithValue("@Auto_Parts_id", dgv_Add_job_card.Rows[i].Cells[9].Value);
                            sd.Parameters.AddWithValue("@Repair_id", dgv_Add_job_card.Rows[i].Cells[10].Value);
                            sd.Parameters.AddWithValue("@Provider_id", dgv_Add_job_card.Rows[i].Cells[11].Value);
                            sd.Parameters.AddWithValue("@Installation_id", dgv_Add_job_card.Rows[i].Cells[12].Value);
                            sd.ExecuteNonQuery();
                            con.Close();
                            
                        }
}

void FillComboBoxRepair()
       {
           try
           {
               con.Open();
               s = "select * from Repair_Type";
               sd = new SqlCommand(s,con);
               sda = sd.ExecuteReader();
               while(sda.Read())
               {
                   string Repair_type = sda.GetString(1);
                   CB_Repair_type.Items.Add(Repair_type);
               }
               con.Close();
           }
           catch(Exception ex)
           {
               MessageBox.Show(ex.Message);
           }
       }

       void FillComboBoxProviders()
       {
           try
           {
               con.Open();
               s = "select * from Providers";
               sd = new SqlCommand(s, con);
               sda = sd.ExecuteReader();
               while (sda.Read())
               {
                   string Provider_desc = sda.GetString(2);
                   CB_Providers_desc.Items.Add(Provider_desc);
               }
               con.Close();
           }
           catch (Exception ex)
           {
               MessageBox.Show(ex.Message);
           }
       }