Help me put with this mapping profile

Question

So there is this add class method and is giving a maping type error i amunable to understand why
[HttpPost]
public async Task<IActionResult> AddClass(StudyClassDto studyClassDto)
{
var studyclass = mapper.Map<StudyClass>(studyClassDto);
uow.StudyClassRepository.AddStudyClass(studyclass);
await uow.SaveAsync();
return Ok();
}
and the mapping type

            CreateMap<StudyClassDto, StudyClass>()  
                .ForMember(dest => dest.AppUserId, opt => opt.MapFrom(src => src.TeacherId));  

i just need the id here