private void SortGroups(string sort)
        {
            DataTable dt = allGroups.DataTable();
            if (sort != string.Empty)
                dt.DefaultView.Sort = sort;

            allGroups = new GroupCollection();
            foreach (DataRowView drv in dt.DefaultView)
            {
                Group group = new Group((int)drv["GroupID"]);
                group.MatchScore = Convert.ToDecimal(drv["MatchScore"]);
                allGroups.Add(group);
            }
        }