I am trying to create a simple ArcGIS Server SOAP consumer by C# like below snippet but I am getting error on NAService_NAServeras illustrated in attached image. Can you please let me know which namespace I have to use?

I am already using this namespaces
using ESRI.ArcGIS.esriSystem;
using ESRI.ArcGIS.Server;
using ESRI.ArcGIS.Geometry;
using ESRI.ArcGIS.Geodatabase;
using ESRI.ArcGIS.Carto;
but they are not doing the job!
using System;
using System.Collections.Generic;
using System.Linq;
using System.Text;
using System.Threading.Tasks;
using ESRI.ArcGIS.esriSystem;
using ESRI.ArcGIS.Server;
using ESRI.ArcGIS.Geometry;
using ESRI.ArcGIS.Geodatabase;
using ESRI.ArcGIS.Carto;
namespace ConsoleApplication1
{
class Program
{
static void Main(string[] args)
{
private void SolveRoute()
{
// Connect to server
NAService_NAServer naService = new NAService_NAServer();
naService.Url = "http://localhost/ArcGIS/services/NetworkAnalysisService/MapServer/NAServer");
//Get Route layers
string[] routeLayers = naService.GetNALayerNames(esriNAServerLayerType.esriNAServerRouteLayer);
// Get the default settings for the first route layer
NAServerRouteParams naServerRouteParams = (NAServerRouteParams)naService.GetSolverParameters(routeLayers[0]);
// Create 2 stops as property sets
List<PropertySet> propertySets = new List<PropertySet>(2);
propertySets.Add(CreatePropertySet("My starting point", -117.195905, 34.057783));
propertySets.Add(CreatePropertySet("My ending point", -117.180943, 34.056286));
// Set the property sets on a NAServerPropertySets object and set on the routeParams object
NAServerPropertySets naServerPropertySets = new NAServerPropertySets();
naServerPropertySets.PropertySets = propertySets.ToArray();
naServerRouteParams.Stops = naServerPropertySets;
// specify to return compact directions
naServerRouteParams.ReturnCompactDirections = true;
// Solve
NAServerRouteResults naServerRouteResults = (NAServerRouteResults)naServer.Solve(naServerRouteParams);
// Output directions
NACompactStreetDirections streetDirections = naServerRouteResults.CompactDirections[0];
StringBuilder sb = new StringBuilder();
sb.AppendFormat("DriveTime = {0}", streetDirections.Summary.TotalDriveTime);
sb.AppendLine();
foreach (NACompactStreetDirection streetDirection in streetDirections.Directions)
{
sb.AppendLine(streetDirection.Text);
}
Console.WriteLine(sb.ToString());
}
}
}
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