Not able to fetch Menu label from ConnectApi.getCommunityNavigationMenu()

I tried using ConnectApi.getCommunityNavigationMenu() to fetch menu-labels but it is returning null, this is the type of menu, 

PIECE OF CODE========================

  public static  List<ConnectApi.NavigationMenuItem> getNavigationMenuItems(String strNavDevName){

        //method to get NetworkId of the logged-in user

        String strNetworkId= Network.getNetworkId();

        List<ConnectApi.NavigationMenuItem> navMenu;

        ConnectApi.PublishStatus publishStatus =ConnectApi.PublishStatus.LIVE;

            try{

                if(!Test.isRunningTest()){

                ConnectApi.NavigationMenuItemCollection navDetails=ConnectApi.NavigationMenu.getCommunityNavigationMenu(strNetworkId,null,strNavDevName,publishStatus,false, false,null);

                navMenu =navDetails.menuItems;

                }

                else{

                String strConnectLabelTestData='testLabel-ActionValue_String';

                    ConnectApi.NavigationMenuItemActionType conMenActionType;

                    ConnectApi.NavigationMenuItem navMenuItem=new ConnectApi.NavigationMenuItem();

                    navMenuItem.Label=strConnectLabelTestData;

                    navMenuItem.actionValue=strConnectLabelTestData;

                    navMenuItem.actionType=conMenActionType;

                    navMenu.add(navMenuItem);

                 }

            }

        catch(Exception ex){

            PMC_ErrorLogClass.processException(ex); // MDErrorLog

        }

        return navMenu;

    }

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I am putting correct developer name of menulist, but it is returning null , I checked in the debug log, also the status of menuitems are live.

kindly help

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