I am trying to write a hello world type program for using virtual channels in the windows terminal services client.

public partial class Form1 : Form
{
    public Form1()
    {
        InitializeComponent();

    }
    IntPtr mHandle = IntPtr.Zero;
    private void Form1_Load(object sender, EventArgs e)
    {
        mHandle = NativeMethods.WTSVirtualChannelOpen(IntPtr.Zero, -1, "TSCRED");
    }

    private void button1_Click(object sender, EventArgs e)
    {
        int bufferSize = 1024;
        byte[] buffer = new byte[bufferSize];
        int bytesRead = 0;
        NativeMethods.WTSVirtualChannelRead(mHandle, 0, buffer, bufferSize, ref bytesRead);
        if (bytesRead != 0)
        {
            MessageBox.Show("Got no Data");
        }
        else
        {
            MessageBox.Show("Got data: " + bytesRead);
        }
    }

    protected override void Dispose(bool disposing)
    {
        if (mHandle != System.IntPtr.Zero)
        {
            NativeMethods.WTSVirtualChannelClose(mHandle);
        }
        base.Dispose(disposing);

    }
}

internal static class NativeMethods
{
    [DllImport("Wtsapi32.dll")]
    public static extern IntPtr WTSVirtualChannelOpen(IntPtr server,
        int sessionId, [MarshalAs(UnmanagedType.LPStr)] string virtualName);

    [DllImport("Wtsapi32.dll", SetLastError = true)]
    public static extern bool WTSVirtualChannelRead(IntPtr channelHandle, long timeout,
            byte[] buffer, int length, ref int bytesReaded);

    [DllImport("Wtsapi32.dll")]
    public static extern bool WTSVirtualChannelClose(IntPtr channelHandle);
}

On NativeMethods.WTSVirtualChannelRead(mHandle, 0, buffer, bufferSize, ref bytesRead); I get the following error every time.

System.AccessViolationException was unhandled by user code
  Message=Attempted to read or write protected memory. This is often an indication that other memory is corrupt.
  Source=RemoteForm
  StackTrace:
       at RemoteForm.NativeMethods.WTSVirtualChannelRead(IntPtr channelHandle, Int64 timeout, Byte[] buffer, Int32 length, Int32& bytesReaded)
       at RemoteForm.Form1.button1_Click(Object sender, EventArgs e) in E:\Visual Studio 2010\Projects\RemoteForm\Form1.cs:line 31
       at System.Windows.Forms.Control.OnClick(EventArgs e)
       at System.Windows.Forms.Button.OnClick(EventArgs e)
       at System.Windows.Forms.Button.OnMouseUp(MouseEventArgs mevent)
       at System.Windows.Forms.Control.WmMouseUp(Message& m, MouseButtons button, Int32 clicks)
       at System.Windows.Forms.Control.WndProc(Message& m)
       at System.Windows.Forms.ButtonBase.WndProc(Message& m)
       at System.Windows.Forms.Button.WndProc(Message& m)
       at System.Windows.Forms.Control.ControlNativeWindow.OnMessage(Message& m)
       at System.Windows.Forms.Control.ControlNativeWindow.WndProc(Message& m)
       at System.Windows.Forms.NativeWindow.Callback(IntPtr hWnd, Int32 msg, IntPtr wparam, IntPtr lparam)
  InnerException:

I am sending the data from the MSTSC COM object and ActiveX controll.

public partial class Form1 : Form
{
    public Form1()
    {
        InitializeComponent();

    }

    private void Form1_Load(object sender, EventArgs e)
    {
        rdp.Server = "schamberlainvm";
        rdp.UserName = "TestAcct";
        IMsTscNonScriptable secured = (IMsTscNonScriptable)rdp.GetOcx();
        secured.ClearTextPassword = "asdf";
        rdp.CreateVirtualChannels("TSCRED");
        rdp.Connect();
    }

    private void button1_Click(object sender, EventArgs e)
    {
        rdp.SendOnVirtualChannel("TSCRED", "This is a test");
    }
}
//Designer code
// 
// rdp
// 
this.rdp.Enabled = true;
this.rdp.Location = new System.Drawing.Point(12, 12);
this.rdp.Name = "rdp";
this.rdp.OcxState = ((System.Windows.Forms.AxHost.State)(resources.GetObject("rdp.OcxState")));
this.rdp.Size = new System.Drawing.Size(1092, 580);
this.rdp.TabIndex = 0;

Any help on this would be greatly appreciated.