EntityFramework, Nested Models and Automapper issue

Hi
I have a nested model, my problem is when I try an update  the base model with the nests, it simply Update with  nests table
Mapper.CreateMap<UserBankingAndEmployerVM, User>() .ForMember(dest => dest.UserAddress, opt => opt.MapFrom(src => { return new UserAddress() { RentOrOwn = src.RentOrOwn, DurationOfTimeAtThisLocation = src.DurationOfTimeAtThisLocation }; }));
I have write code  with update user address. i have use code first database entity EntityFramework but i am getting  "UserID' is part of the object's key information and cannot be modified" error.

Thanks in advance