Virtual device is unresponsive

I have written custom skill which discovers virtual devices. When I run it on emulator is returns positive acknowledgement 'OK'. But when I try to access the current status of that device through alexa app it shows device is unresponsive and always show device is off.

lambda Function :

exports.handler = function (request, context) {
    if (request.directive.header.namespace === 'Alexa.Discovery' && request.directive.header.name === 'Discover') {
        log("DEBUG:", "Discover request",  JSON.stringify(request));
        handleDiscovery(request, context, "");
    }
    else if (request.directive.header.namespace === 'Alexa.PowerController') {
        if (request.directive.header.name === 'TurnOn' || request.directive.header.name === 'TurnOff') {
            log("DEBUG:", "TurnOn or TurnOff Request", JSON.stringify(request));
            handlePowerControl(request, context);
        }
    }


    function handleDiscovery(request, context) {
        var payload = {
            "endpoints":
            [
                {
                    "endpointId": "6f31dc57-d033-4cbd-8020-6bbb516bcab",
                    "manufacturerName": "Smart Device Company",
                    "friendlyName": "Bedroom Outlet",
                    "description": "Smart Device Switch",
                    "displayCategories": ["LIGHT"],
                    "isReachable": true,
                    "cookie": {
                        "key1": "arbitrary key/value pairs for skill to reference this endpoint.",
                        "key2": "There can be multiple entries",
                        "key3": "but they should only be used for reference purposes.",
                        "key4": "This is not a suitable place to maintain current endpoint state."
                    },
                    "capabilities":
                    [
                        {
                            "type":"AlexaInterface",
                            "interface":"Alexa.ColorTemperatureController",
                            "version":"3",
                            "properties":{
                                "supported":[
                                {
                                  "name":"colorTemperatureInKelvin"
                                }
                            ],
                            "proactivelyReported":true,
                            "retrievable":true
                            }
                        },
                        {
                            "type": "AlexaInterface",
                            "interface": "Alexa.PowerController",
                            "version": "3",
                            "properties": {
                            "supported": [ {
                                "name": "powerState"
                            } ],
                            "proactivelyReported": true,
                            "retrievable": true
                            }
                        },
                        {
                            "type":"AlexaInterface",
                            "interface":"Alexa",
                            "version":"3"
                        },
                        {
                            "type":"AlexaInterface",
                            "interface":"Alexa.ColorController",
                            "version":"3",
                            "properties":{
                                "supported":[
                                {
                                    "name":"color"
                                }
                            ],
                            "proactivelyReported":true,
                            "retrievable":true
                            }
                        }
                    ]
                }
            ]
        };
        var header = request.directive.header;
        header.name = "Discover.Response";
        log("DEBUG", "Discovery Response: ", JSON.stringify({ header: header, payload: payload }));
        context.succeed({ event: { header: header, payload: payload } });
    }


    function log(message, message1, message2) {
        console.log(message + message1 + message2);
    }


    function handlePowerControl(request, context) {
        // get device ID passed in during discovery
        var requestMethod = request.directive.header.name;
        // get user token pass in request
        var requestToken = request.directive.endpoint.scope.token;
        var powerResult;


        if (requestMethod === "TurnOn") {


            // Make the call to your device cloud for control 
            // powerResult = stubControlFunctionToYourCloud(endpointId, token, request);
            powerResult = "ON";
        }
       else if (requestMethod === "TurnOff") {
            // Make the call to your device cloud for control and check for success 
            // powerResult = stubControlFunctionToYourCloud(endpointId, token, request);
            powerResult = "OFF";
        }
        var contextResult = {
            "properties": [{
                "namespace": "Alexa.PowerController",
                "name": "powerState",
                "value": powerResult,
                "timeOfSample": "2017-09-03T16:20:50.52Z", //retrieve from result.
                "uncertaintyInMilliseconds": 500
            }]
        };
        var tok = request.directive.endpoint.scope.token;
        var endpointResult = {
            "scope":  {
                "type": "BearerToken",
                "token": tok
            },
            "endpointId": "6f31dc57-d033-4cbd-8020-6bbb516bcab"
        };
        var responseHeader = request.directive.header;
        responseHeader.name = "Response";
        responseHeader.namespace= "Alexa";
        responseHeader.messageId = responseHeader.messageId + "-R";
        var response = {
            context: contextResult,
            event: {
                header: responseHeader,
                endpoint: endpointResult,
                payload: {}
            }
        };
        log("DEBUG", "Alexa.PowerController ", JSON.stringify(response));
        context.succeed(response);
    }
};

test - event :
***************************

{
  "directive": {
    "header": {
      "namespace": "Alexa.PowerController",
      "name": "TurnOn",
      "payloadVersion": "3",
      "messageId": "1bd5d003-31b9-476f-ad03-71d471922820",
      "correlationToken": "dFMb0z+PgpgdDmluhJ1LddFvSqZ/jCc8ptlAKulUj90jSqg=="
    },
    "endpoint": {
      "scope": {
        "type": "BearerToken",
        "token": "access-token-from-1111"
      },
      "endpointId": "demo_id",
      "cookie": {}
    },
    "payload": {}
  }
}

********************************************

Response : 

 **************************************************************************
Response:
{
  "context": {
    "properties": [
      {
        "namespace": "Alexa.PowerController",
        "name": "powerState",
        "value": "ON",
        "timeOfSample": "2017-09-03T16:20:50.52Z",
        "uncertaintyInMilliseconds": 500
      }
    ]
  },
  "event": {
    "header": {
      "namespace": "Alexa",
      "name": "Response",
      "payloadVersion": "3",
      "messageId": "1bd5d003-31b9-476f-ad03-71d471922820-R",
      "correlationToken": "dFMb0z+PgpgdDmluhJ1LddFvSqZ/jCc8ptlAKulUj90jSqg=="
    },
    "endpoint": {
      "scope": {
        "type": "BearerToken",
        "token": "access-token-from-1111"
      },
      "endpointId": "6f31dc57-d033-4cbd-8020-6bbb516bcab"
    },
    "payload": {}
  }
}