c#条形码打印为什么会打印时中间空几个纸张    就是每次打印是都是空5张纸  打印条形码  在空5张  纸   在打印       为什么 会出现中间空纸张的现象？？？

using System;
using System.Collections.Generic;
using System.ComponentModel;
using System.Data;
using System.Drawing;
using System.Text;
using System.Drawing.Printing;
using System.Windows.Forms;

namespace Code128Test
{
    public partial class FrmTest : Form
    {
        string inputString;
        public FrmTest()
        {
            InitializeComponent();
        }

        private string Get128CodeString(string inputData)
        {
            string result;
            int checksum = 104;
            for (int ii = 0; ii < inputData.Length; ii++)
            {
                if (inputData[ii] >= 32)
                {
                    checksum += (inputData[ii] - 32) * (ii + 1);
                }
                else
                {
                    checksum += (inputData[ii] + 64) * (ii + 1);
                }
            }
            checksum = checksum % 103;
            if (checksum < 95)
            {
                checksum += 32;
            }
            else
            {
                checksum += 100;
            }
            result = Convert.ToChar(204) + inputData.ToString() + Convert.ToChar(checksum) + Convert.ToChar(206);
            return result;
        }

        public void PrintLable()
        {
            PrintDocument pd = new PrintDocument();
            StandardPrintController controler = new StandardPrintController();

            try
            {

              
                pd.PrintPage += new PrintPageEventHandler(this.PrintCustomLable);
                pd.PrintController = controler;
                Margins margins = new Margins(10, 10, 10, 10);
                pd.DefaultPageSettings.Margins = margins;
                pd.DefaultPageSettings.PaperSource.RawKind = 1;
                pd.Print();
               
                return;
            }
            catch (Exception err)
            {
                Console.WriteLine(err.Message);
                return;
            }
            finally
            {
                pd.Dispose();
            }

        }
        public void PrintCustomLable(Object Sender, PrintPageEventArgs av)
        {
            Font ft1 = new System.Drawing.Font("Times New Roman", 12, FontStyle.Regular, GraphicsUnit.World);
            Font ft2 = new System.Drawing.Font("Code 128", 38, FontStyle.Regular, GraphicsUnit.World);
            Brush br = new SolidBrush(Color.Black);
            Margins margins = new Margins(50, 50, 50, 150);
            av.PageSettings.Margins = margins;

            av.Graphics.DrawString(Get128CodeString(inputString), ft2, br, 105, -3);
            av.Graphics.DrawString(inputString, ft1, br, 130, 45);
            av.HasMorePages = false;

         
          //  av.Graphics.PageUnit = GraphicsUnit.Millimeter;
        }

        private void btnPrint_Click(object sender, EventArgs e)
        {
            inputString = txtInput.Text;
            lblBarCode.Text = Get128CodeString(inputString);
            PrintLable();
        }

    }
}