Problems with Objectstatemanager when updating a Model

Question

I’m having trouble updating a model, the code below is working correctly when I give GET in a context model edits on the screen (View) and I give a Submit everything ok but when I have a data grid where I load several messages and for example I will check (checkbox) on this grid to change an active flag to inactive it does not proceed but also not error ?

I think it has to do with Objectstatemanager in all actions that it performs correctly State is with Datached but when the does not update without giving any error State is as Unchanged.

A great note to help me is that this method always comes with my Model ID it is only used to Edit and to insert I have another method.

Follows the method

       public void Edit(TEntity entity)
        {
            var entry = _context.Entry<TEntity>(entity);
            var pkey = _dbSet.Create().GetType().GetProperty("ID").GetValue(entity);

            if ((entry.State == EntityState.Detached))
            {
                var set = _context.Set<TEntity>();
                TEntity attachedEntity = set.Find(pkey);

                if (attachedEntity != null)
                {
                    var attachedEntry = _context.Entry(attachedEntity);
                    attachedEntry.CurrentValues.SetValues(entity);
                }
                else
                {
                    entry.State = EntityState.Modified;
                }
            }

            try
            {
                _context.SaveChanges();
            }
            catch (System.Data.Entity.Validation.DbEntityValidationException ex)
            {
                StringBuilder sb = new StringBuilder();

                foreach (var failure in ex.EntityValidationErrors)
                {
                    sb.AppendFormat("{0} Falha da validação ", failure.Entry.Entity.GetType());
                    foreach (var error in failure.ValidationErrors)
                    {
                        sb.AppendFormat("- {0} : {1}", error.PropertyName, error.ErrorMessage);
                        sb.AppendLine();
                    }
                }

                throw new System.Data.Entity.Validation.DbEntityValidationException("Erros da validação da Entidade: " + sb.ToString(), ex);
            }
        }

Who can give me a way out so that always this method of an independent UPDATE if it comes with the State, I am grateful. there is one more thing I’ve been stirring and had situations where he gave error of existing Objectstatemanager too.