The INSERT statement conflicted with the FOREIGN KEY constraint "FK_Installments_Loan". The conflict occurred in database, table "dbo.Loan", column 'Loan_id'. The statement has been terminated.

for (i = 0; i < dataGridView1.Rows.Count; i++)
                 {


                     string query = "insert into Installments(Installment_no,Loan_id,Date,Amount)values(@Installment_no,@Loan_id,@Date,@Amount)";
                     cmd = new SqlCommand(query, cn);
                     //MessageBox.Show(query);



                     cmd.Parameters.AddWithValue("@Loan_id", dataGridView1.Rows[i].Cells["Loanid"].Value);
                     cmd.Parameters.AddWithValue("@Date", dataGridView1.Rows[i].Cells["Date"].Value);
                     cmd.Parameters.AddWithValue("@Amount", dataGridView1.Rows[i].Cells["Amount"].Value);
                     cmd.Parameters.AddWithValue("@Installment_no", dataGridView1.Rows[i].Cells["installmentno"].Value);
                     cn.Open();
                     cmd.ExecuteNonQuery();
                     cn.Close();
                 }

                 MessageBox.Show("Record Stored Successfully", "Success Message", MessageBoxButtons.OK, MessageBoxIcon.Information);
             }