Automapper Mapper.CreateMapExpression ArgumentException Linq2SQL

Automapper Mapper.CreateMapExpression ArgumentException Linq2SQL

I use Linq2SQL and automapper
class Bootstrapper{
Mapper.CreateMap<PageEntity, Page>()
.ForMember(dst => dst.Category, opt => opt.MapFrom(src =>
src.PageCategoryEntity));
Mapper.CreateMap<ContactEntity, Contact>();
}
class Repository<TModel,TEntity>
where TModel : BaseModel
where TEntity : Entity{
public IQueryable<TModel> GetAll()
{
db=new DataClassesDataContext();
var data = db.GetTable<TEntity>().Select(x => x);
var expression = Mapper.CreateMapExpression<TEntity, TModel>();
return data.Select(expresion);
}
}
Mapper.CreateMapExpression() for Page, PageEntity generate
ArgumentException, but for ContactEntity, Contact this method works off
without exceptions.
How to solve the problem for Page, PageEntity?