实体不会从Azure表中删除

当我试图删除实体时，Visual Studio总是在"serviceContext.DeleteObject（entity）；"行上崩溃，并说"上下文当前没有跟踪实体。"有人知道为什么以及如何修复它吗？

    CloudTableQuery<ScheduleEntity> query = scheduleManNot.retrieveSchedule();
            //Checks every entry 
            foreach (ScheduleEntity entity in query)
            {
                comparison = System.DateTime.Compare(entity.eventTime, time);
                if (comparison <= 0)
                {
                    changeConfirmation = scheduleManNot.changeInstanceCount(entity.subscriptionID, entity.amount, entity.serviceName);
                    if (changeConfirmation == false)
                    {
                        Console.WriteLine("Configuration Change failed");
                    }
                    if (changeConfirmation == true)
                    {
                        Console.WriteLine("Configuration Change Succeeded");
                        Console.WriteLine(entity.serviceName + " had its instance count changed to " + entity.amount); 

                       serviceContext.AttachTo("schedule", entity, "*");
                       serviceContext.DeleteObject(entity);
                        //Submit the operation to the table service
                        serviceContext.SaveChangesWithRetries();