How to Include object in c#

Question

I have 3 table

public class Request{
    [Key]
    public int ID { set; get; }
    [Required]
    [MaxLength(128)]
    public string  UserId{ set; get; }
    [ForeignKey("UserId")]
    public virtual AppUser AppUser { get; set; }  
} 
public class AppUser{  
    [Key]
    public int ID { set; get; }
    [Required]
    public int GroupID { get; set; }
    [ForeignKey("GroupID")]
    public virtual Group Group { get; set; }
}
 public class Group{
    [Key]
    public int ID { set; get; }
    public string Name { get; set; }
}

I have function GetAll

    public IEnumerable<T> GetAll(string[] includes = null)
      {
        if (includes != null && includes.Count() > 0)
        {
            var query = dataContext.Set<T>().Include(includes.First());
            foreach (var include in includes.Skip(1))
                query = query.Include(include);
            return query.AsQueryable();
        }

        return dataContext.Set<T>().AsQueryable();
    }

When run function get All

     request.GetAll(new string[] {"AppUser"});

the result have object appUser but in AppUser ,Group is null . How i include group in AppUser