[Cannot communicate with the PLC with the specified UnitID!]

I am using the demo ComDriver code as follows:

using System;
using Unitronics.ComDriver;

namespace Com_Drive_Net___Example
{
	class AccessClass
	{
		static PLC plc;

		public static void Test (){

			Ethernet eth = new Ethernet ("192.168.1.152", 20256, EthProtocol.TCP, 3, 3000);

			try{
				plc = PLCFactory.GetPLC(eth, 0);
				plc.EventAbortCompleted+=new PLC.AbortCompletedDelegate(plc_EventAbortCompleted);
			}catch(Exception e){
				eth.Disconnect();
				Console.WriteLine ("Error1:"+e.Message+"-->("+e.TargetSite+")"+e.StackTrace+"-->"+e.Source);
			}
			try{
				Console.WriteLine(plc.Version.OPLCModel);
				Console.WriteLine (plc.PlcName);
				Console.WriteLine(eth.Connected);
				Console.WriteLine(plc.UnitId);
			}catch(Exception e){
				eth.Disconnect();
				Console.WriteLine ("Error2:"+e.Message+"-->("+e.TargetSite+")"+e.StackTrace);
			}
	
			Console.Read ();
		} 
		public static void plc_EventAbortCompleted(){
			Console.WriteLine ("dunno");
		}
	}
}

It is pretty much straight out of the book.  

 

I continue to get the following error:

Unhandled Exception:
Unitronics.ComDriver.ComDriveExceptions: Cannot communicate with the PLC with the specified UnitID!
  at Unitronics.ComDriver.PLC..ctor (Int32 unitId, Unitronics.ComDriver.Channel channel, Boolean suppressEthernetHeader) [0x00000] in <filename unknown>:0 
  at Unitronics.ComDriver.PLCFactory.getPLC (Unitronics.ComDriver.Channel& channel, Int32 unitId, System.Boolean& isConnected, Boolean suppressEthernetHeader) [0x00000] in <filename unknown>:0 
[ERROR] FATAL UNHANDLED EXCEPTION: Unitronics.ComDriver.ComDriveExceptions: Cannot communicate with the PLC with the specified UnitID!
  at Unitronics.ComDriver.PLC..ctor (Int32 unitId, Unitronics.ComDriver.Channel channel, Boolean suppressEthernetHeader) [0x00000] in <filename unknown>:0 
  at Unitronics.ComDriver.PLCFactory.getPLC (Unitronics.ComDriver.Channel& channel, Int32 unitId, System.Boolean& isConnected, Boolean suppressEthernetHeader) [0x00000] in <filename unknown>:0 

I have tried three different versions of Unitronics.ComDriver.dll, dated 7/26/15, 7/29/15 and compiled myself yesterday, 3/2/16.  Same error on everyone.  I am not a C# expert by no means, but I can't see what I might be doing wrong.

 

We set the the PLC to TCP/slave and set its Socket 0 Port to 20256 (mostly in desperation)

 

I'm not sure what to try next?

 

Thanks