In my nhibernet with .Net MVC web application does not supporting simaltenious service calling

We are useing Nhibernet MVC Artecture Code first approch in C# Asp.Net with Web API’s,SQL Server as Backend Database System.
My Current Server Configuration is Windows Server 2016 with 16GB Ram 4Core processor and Hosted it on Microsft Azure

My Code Is

                long ClienTypeId = 0;
                var clientMatrixRepository = Container.Resolve<Model.ORM.Repository<int, ClientMatrix>>();

                var ClientMatrixDBEntities = clientMatrixRepository.GetMany(c => c.IsActive == true && c.Client !=null && c.Client.Id == ClientId).FirstOrDefault();
                if (ClientMatrixDBEntities == null)
                    return ClienTypeId;

                var config = new MapperConfiguration(con => con.CreateMap<ClientMatrix, ClientMatrixEntity>());
                IMapper mapper = config.CreateMapper();
                var ClientMatrixEntities = mapper.Map<ClientMatrix, ClientMatrixEntity>(ClientMatrixDBEntities);
                if (ClientMatrixEntities == null)
                    throw new ApplicationException("Mapping error");

                ClienTypeId = Convert.ToInt64(ClientMatrixEntities.ClientType.Id);
                return ClienTypeId;

Occurred Exception is :

Exception is ‘could not load an entity: [LegalNext.Model.ClientType#1]
[SQL: SELECT clienttype0_.Id as Id24_0_, clienttype0_.Name as Name24_0_, clienttype0_.Description as Descript3_24_0_, clienttype0_.IsActive as IsActive24_0_ FROM [ClientType] clienttype0_ WHERE clienttype0_.Id=?]’