Write to a printer using vb.net

I'm trying to write a vb.net program to write a text file to a printer

I found some code on Microsoft .com and I have copied it to Visual Studio.  Here is the code:

Imports System.IO
Imports System.Drawing.Printing
Imports System.Runtime.InteropServices

Public Class Form1

    Private Sub Button1_Click(sender As System.Object, e As System.EventArgs) Handles Button1.Click
        Dim ofd As New OpenFileDialog()
        If ofd.ShowDialog(Me) Then
            Dim pd As New PrintDialog()
            pd.PrinterSettings = New PrinterSettings()
            If (pd.ShowDialog() = Windows.Forms.DialogResult.OK) Then
                RawPrinterHelper.SendFileToPrinter(pd.PrinterSettings.PrinterName, ofd.FileName)
            End If
        End If
    End Sub 'Button1_Click

    Private Sub Button2_Click(sender As System.Object, e As System.EventArgs) Handles Button2.Click
        Dim s As String
        Dim pd As New PrintDialog()

        s = "Hello, this is a test"
        pd.PrinterSettings = New PrinterSettings()
        If (pd.ShowDialog() = DialogResult.OK) Then
            rawprinterhelper.sendstringtoprinter(pd.PrinterSettings.PrinterName, s)
        End If
    End Sub 'Button2_Click
End Class
Public Class RawPrinterHelper
    ' Structure and API declarions:
    <StructLayout(LayoutKind.Sequential, CharSet:=CharSet.Unicode)> _
    Structure DOCINFOW
        <MarshalAs(UnmanagedType.LPWStr)> Public pDocName As String
        <MarshalAs(UnmanagedType.LPWStr)> Public pOutputFile As String
        <MarshalAs(UnmanagedType.LPWStr)> Public pDataType As String
    End Structure

    <DllImport("winspool.Drv", EntryPoint:="OpenPrinterW", _
       SetLastError:=True, CharSet:=CharSet.Unicode, _
       ExactSpelling:=True, CallingConvention:=CallingConvention.StdCall)> _
    Public Shared Function OpenPrinter(ByVal src As String, ByRef hPrinter As IntPtr, ByVal pd As Long) As Boolean
    End Function
    <DllImport("winspool.Drv", EntryPoint:="ClosePrinter", _
       SetLastError:=True, CharSet:=CharSet.Unicode, _
       ExactSpelling:=True, CallingConvention:=CallingConvention.StdCall)> _
    Public Shared Function ClosePrinter(ByVal hPrinter As IntPtr) As Boolean
    End Function
    <DllImport("winspool.Drv", EntryPoint:="StartDocPrinterW", _
       SetLastError:=True, CharSet:=CharSet.Unicode, _
       ExactSpelling:=True, CallingConvention:=CallingConvention.StdCall)> _
    Public Shared Function StartDocPrinter(ByVal hPrinter As IntPtr, ByVal level As Int32, ByRef pDI As DOCINFOW) As Boolean
    End Function
    <DllImport("winspool.Drv", EntryPoint:="EndDocPrinter", _
       SetLastError:=True, CharSet:=CharSet.Unicode, _
       ExactSpelling:=True, CallingConvention:=CallingConvention.StdCall)> _
    Public Shared Function EndDocPrinter(ByVal hPrinter As IntPtr) As Boolean
    End Function
    <DllImport("winspool.Drv", EntryPoint:="StartPagePrinter", _
       SetLastError:=True, CharSet:=CharSet.Unicode, _
       ExactSpelling:=True, CallingConvention:=CallingConvention.StdCall)> _
    Public Shared Function StartPagePrinter(ByVal hPrinter As IntPtr) As Boolean
    End Function
    <DllImport("winspool.Drv", EntryPoint:="EndPagePrinter", _
       SetLastError:=True, CharSet:=CharSet.Unicode, _
       ExactSpelling:=True, CallingConvention:=CallingConvention.StdCall)> _
    Public Shared Function EndPagePrinter(ByVal hPrinter As IntPtr) As Boolean
    End Function
    <DllImport("winspool.Drv", EntryPoint:="WritePrinter", _
       SetLastError:=True, CharSet:=CharSet.Unicode, _
       ExactSpelling:=True, CallingConvention:=CallingConvention.StdCall)> _
    Public Shared Function WritePrinter(ByVal hPrinter As IntPtr, ByVal pBytes As IntPtr, ByVal dwCount As Int32, ByRef dwWritten As Int32) As Boolean
    End Function

    ' SendBytesToPrinter()
    ' When the function is given a printer name and an unmanaged array of  
    ' bytes, the function sends those bytes to the print queue.
    ' Returns True on success or False on failure.
    Public Shared Function SendBytesToPrinter(ByVal szPrinterName As String, ByVal pBytes As IntPtr, ByVal dwCount As Int32) As Boolean
        Dim hPrinter As IntPtr      ' The printer handle.
        Dim dwError As Int32        ' Last error - in case there was trouble.
        Dim di As DOCINFOW          ' Describes your document (name, port, data type).
        Dim dwWritten As Int32      ' The number of bytes written by WritePrinter().
        Dim bSuccess As Boolean     ' Your success code.

        ' Set up the DOCINFO structure.
        With di
            .pDocName = "My Visual Basic .NET RAW Document"
            .pDataType = "RAW"
        End With
        ' Assume failure unless you specifically succeed.
        bSuccess = False
        If OpenPrinter(szPrinterName, hPrinter, 0) Then
            If StartDocPrinter(hPrinter, 1, di) Then
                If StartPagePrinter(hPrinter) Then
                    ' Write your printer-specific bytes to the printer.
                    bSuccess = WritePrinter(hPrinter, pBytes, dwCount, dwWritten)
                    EndPagePrinter(hPrinter)
                End If
                EndDocPrinter(hPrinter)
            End If
            ClosePrinter(hPrinter)
        End If
        ' If you did not succeed, GetLastError may give more information
        ' about why not.
        If bSuccess = False Then
            dwError = Marshal.GetLastWin32Error()
        End If
        Return bSuccess
    End Function ' SendBytesToPrinter()

    ' SendFileToPrinter()
    ' When the function is given a file name and a printer name,
    ' the function reads the contents of the file and sends the
    ' contents to the printer.
    ' Presumes that the file contains printer-ready data.
    ' Shows how to use the SendBytesToPrinter function.
    ' Returns True on success or False on failure.
    Public Shared Function SendFileToPrinter(ByVal szPrinterName As String, ByVal szFileName As String) As Boolean
        ' Open the file.
        Dim fs As New FileStream(szFileName, FileMode.Open)
        ' Create a BinaryReader on the file.
        Dim br As New BinaryReader(fs)
        ' Dim an array of bytes large enough to hold the file's contents.
        Dim bytes(fs.Length) As Byte
        Dim bSuccess As Boolean
        ' Your unmanaged pointer.
        Dim pUnmanagedBytes As IntPtr

        ' Read the contents of the file into the array.
        bytes = br.ReadBytes(fs.Length)
        ' Allocate some unmanaged memory for those bytes.
        pUnmanagedBytes = Marshal.AllocCoTaskMem(fs.Length)
        ' Copy the managed byte array into the unmanaged array.
        Marshal.Copy(bytes, 0, pUnmanagedBytes, fs.Length)
        ' Send the unmanaged bytes to the printer.
        bSuccess = SendBytesToPrinter(szPrinterName, pUnmanagedBytes, fs.Length)
        ' Free the unmanaged memory that you allocated earlier.
        Marshal.FreeCoTaskMem(pUnmanagedBytes)
        Return bSuccess
    End Function ' SendFileToPrinter()

    ' When the function is given a string and a printer name,
    ' the function sends the string to the printer as raw bytes.
    Public Shared Function SendStringToPrinter(ByVal szPrinterName As String, ByVal szString As String)
        Dim pBytes As IntPtr
        Dim dwCount As Int32
        ' How many characters are in the string?
        dwCount = szString.Length()
        ' Assume that the printer is expecting ANSI text, and then convert
        ' the string to ANSI text.
        pBytes = Marshal.StringToCoTaskMemAnsi(szString)
        ' Send the converted ANSI string to the printer.
        SendBytesToPrinter(szPrinterName, pBytes, dwCount)
        Marshal.FreeCoTaskMem(pBytes)
    End Function
End Class

When I try to run it by clicking Button 1, I am able to select the text file but then I get the error message on the attached Word doc.  The place in the code where it errors is this:

"If OpenPrinter(szPrinterName, hPrinter, 0) Then"

I don't know how to fix this.

TextToPrinterErrorMessaage.docx