This is my code. I got this sample from the Internet and I tried to modify it.

    private void FillGridData()
    {
        //IQueryable<SVC> query = _customerService.GetQueryable();

        _dataContext = new dbServiceModelDataContext();
        var query = from m in _dataContext.SVCs
                    select m;

        query = AddQuerySearchCriteria(query, _grid.SearchForm);

        int totalRows = query.Count();
        _grid.Pager.Init(totalRows);

        if (totalRows == 0)
        {
            _grid.Data = new List<SVC>();
            return;
        }

        query = AddQuerySorting(query, _grid.Sorter);
        query = AddQueryPaging(query, _grid.Pager);

        List<SVC> customers = query.ToList(); //***ERROR IN HERE***//
        _grid.Data = customers;
    }

The error says "Cannot order by type 'System.Object'.", what is the matter? Do you have solution for me?

This is The AddQuerySorting Method THE PROBLEM IS IN HERE
is there anything wrong about the code? :(

    private IQueryable<SVC> AddQuerySorting(IQueryable<SVC> query, Sorter sorter)
    {
        if (String.IsNullOrEmpty(sorter.SortField))
            return query;

        //Used approach from http://www.singingeels.com/Articles/Self_Sorting_GridView_with_LINQ_Expression_Trees.aspx
        //instead of a long switch statement 
        var param = Expression.Parameter(typeof(SVC), "customer");
        var sortExpression = Expression.Lambda<Func<SVC, object>>
                                (Expression.Convert(Expression.Property(param, sorter.SortField), typeof(object)), param);

        if (sorter.SortDirection == SortDirection.Asc)
            query = query.OrderBy(sortExpression);
        else
            query = query.OrderByDescending(sortExpression);

        return query;
    }

here is AddQueryPaging Method

    private IQueryable<SVC> AddQueryPaging(IQueryable<SVC> query, Pager pager)
    {
        if (pager.TotalPages == 0)
            return query;

        query = query.Skip((pager.CurrentPage - 1) * pager.PageSize)
                            .Take(pager.PageSize);
        return query;
    }