Generate new id code with alpha and number format

Question

I create c# project with Access Database and I want to Autogenerated new id (Format as 3 Alphabets 3 Digits) but alphabets change automatically with selection of last form. i tried this but just 1st condition works,

 

void NewAppID()
        {
            try
            {
                OleDbDataAdapter da = new OleDbDataAdapter("select [FormCode] from [Booking] order by [FormCode] desc", conn);
                DataSet ds = new DataSet();
                da.Fill(ds);

                if (lblProName.Text == "Fazal Sun City" || ds.Tables[0].Rows.Count > 0)
                {
                    txtFormCode.Text = "FSC " + (int.Parse(ds.Tables[0].Rows[0][0].ToString()) + 1).ToString();
                }
                else if (lblProName.Text == "Mehran Gold" || ds.Tables[0].Rows.Count > 0)
                {
                    txtFormCode.Text = "MG " + (int.Parse(ds.Tables[0].Rows[0][0].ToString()) + 1).ToString();
                }
                else
                {
                    txtFormCode.Text = "1";
                }

            }
            catch (Exception ex)
            {
                MetroFramework.MetroMessageBox.Show(this, "Error" + ex.Message, "Stop", MessageBoxButtons.OK, MessageBoxIcon.Stop);
            }
        }