Prolog with C#. Access Voilation Error

Question

I am new to Prolog and C#. When I try to integrate Prolog with C# I found some errors. I followed the instructions written at SWI-Prolog website and uses its sample code. When I run the application it give the following error. someone can guide me what to do?? thank you in advance

Error: Message: An unhandled exception of type 'System.AccessViolationException' occurred in SwiPlCs.dll

Code here:

Environment.SetEnvironmentVariable("SWI_HOME_DIR", @"C:\Program Files (x86)\swipl\");
            Environment.SetEnvironmentVariable("PATH", @"C:\Program Files (x86)\swipl\");
            Environment.SetEnvironmentVariable("PATH", @"C:\Program Files (x86)\swipl\bin\");

            if (!PlEngine.IsInitialized)
            {
                String[] param = { "-q"};  // suppressing informational and banner messages
                PlEngine.Initialize(param);
                PlQuery.PlCall("assert(father(martin, inka))");
                PlQuery.PlCall("assert(father(uwe, gloria))");
                PlQuery.PlCall("assert(father(uwe, melanie))");
                PlQuery.PlCall("assert(father(uwe, ayala))");
                using (var q = new PlQuery("father(P, C), atomic_list_concat([P,' is_father_of ',C], L)"))
                {
                    foreach (PlQueryVariables v in q.SolutionVariables)
                        Console.WriteLine(v["L"].ToString());

                    Console.WriteLine("all children from uwe:");
                    q.Variables["P"].Unify("uwe");
                    foreach (PlQueryVariables v in q.SolutionVariables)
                        Console.WriteLine(v["C"].ToString());
                }
                PlEngine.PlCleanup();
                Console.WriteLine("finshed!");
            }