DynamicLinq c#在join中不工作

我在c#项目中使用DynamicLinq.

当我使用"order by"，"skip"等做一个简单的选择时，效果很好。

但是如果你加入了restona一个简单的错误:

Error   3   Instance argument: cannot convert from 'int?' to 'System.Linq.IQueryable'   J:'C#'ERP'ERP'Helpers'ListagemPadrao.cs 23  25  ERP
Error   2   'int?' does not contain a definition for 'OrderBy' and the best extension method overload 'System.Linq.Dynamic.DynamicQueryable.OrderBy(System.Linq.IQueryable, string, params object[])' has some invalid arguments    J:'C#'ERP'ERP'Helpers'ListagemPadrao.cs 23  25  ERP

SQL工作:

var lista =
  from a in db.Usuario.AsQueryable()
      .OrderBy(aOrderna + " " + aOrdenaTipo)
      .Skip(aIniciarNoRegistro)
      .Take(aQtdeRegistro)                    
      select new
      {
          a.UsuarioID,
          a.Nome,
          a.Login,
          a.Email
      };   

SQL not work:

var lista =
  from a in db.Usuario.AsQueryable()
  join b in db.UsuarioAcesso.AsQueryable() on a.UsuarioID equals b.UsuarioID 
      .OrderBy(aOrderna + " " + aOrdenaTipo)
      .Skip(aIniciarNoRegistro)
      .Take(aQtdeRegistro)                    
      select new
      {
          a.UsuarioID,
          a.Nome,
          a.Login,
          a.Email
      };

var lista =
  (from a in db.Usuario.AsQueryable()
  join b in db.UsuarioAcesso.AsQueryable() on a.UsuarioID equals b.UsuarioID   
  select new
  {
      a.UsuarioID,
      a.Nome,
      a.Login,
      a.Email
  })
  .OrderBy(aOrderna + " " + aOrdenaTipo)
  .Skip(aIniciarNoRegistro)
  .Take(aQtdeRegistro);