System.NullReferenceException: Object reference not set to an instance of an object. at Xink.Data.ProfileAdapter.<>c__DisplayClass2.b__0(Member x) at System.Linq.Enumerable.FirstOrDefault[TSource](IEnumerable`1 source, Func`2 predicate) at Xink.Data.ProfileAdapter.GetMemberByNickname(String username, Boolean usecache) at Xink.Controllers.ProductController.XCollectionItemDetail(Int32 id, Int32 TopicId, Int32 Pk_iCatId, String v)