Logon Failure while impersonating

Question

This is a similar question on how to impersonate a logon.

However, I'm running into an issue when attempting to run System.IO.File.Copy() or System.IO.File.Move() while impersonating and receive the following error:

Logon failure: unknown user name or bad password

In my code, I've created a custom class to wrap the proper impersonate code with, so I can call it up like so:

using(var cnn = new {NetworkName}Connection()){
  // Work in the file system under admin privileges
  System.IO.File.Copy("{UNCSourcePath}", "{UNCTargetPath}", true);//Copy file from one server to another, overwrite if necessary
}

This way, I ensure the identity is properly disposed. My wrapper is posted below:

public class {NetworkName}Connection : IDisposable
  {
    [DllImport("advapi32.dll")]
    public static extern int LogonUser(String lpszUserName,String lpszDomain,String lpszPassword,int dwLogonType,int dwLogonProvider,ref IntPtr phToken);

    [DllImport("kernel32.dll", SetLastError = true)]
    [return: MarshalAs(UnmanagedType.Bool)]
    static extern bool CloseHandle(IntPtr hObject);

    IntPtr tokenHandle;
    WindowsIdentity newId;
    public WindowsImpersonationContext User { get; set; }
    public {NetworkName}Connection()
    {
      this.tokenHandle = new IntPtr(0);
      if (LogonUser("{UserName}", "{NetworkName}", "{Password}", 9, 3, ref this.tokenHandle) != 0)
      {
        newId = new WindowsIdentity(tokenHandle);
        this.User = newId.Impersonate();
      }else{
        throw new Exception("Couldn't log onto {NetworkName}.");
      }
    }

    public void Dispose()
    {
      this.User.Dispose();
      CloseHandle(this.tokenHandle);
    }
  }

Within my wrapper, I'm able to successfully validate file existence and create FileInfo objects, but what could be the reason/fix for my application stopping on the Copy function?

Another important note would be that the server I'm connecting to is an old Windows Server 2000 machine. I also have similar code working in a VB.NET application, so I know the logic and credentials are correct.