LINQ Query results and string methods

First of all let me apologize for the wall of code. Basically, I have two two queries against Sharepoint lists. The code seems to work great if I comment a couple of lines. Here is the code:

Global:

private string mUserName = "";
// Entity classes for the Sharepoint Li开发者_StackOverflow中文版sts
private SeatingChartContext _dc;
private EntityList<Seating_chartItem> _seatCharts;
private EntityList<UsersItem> _users;
private EntityList<Excluded_usersItem> _exusers;
private EntityList<RoomsItem> _rooms;
private EntityList<LogsItem> _logs;`

Page Load:

// Get the Lists from Sharepoint
_dc = new SeatingChartContext(SPContext.Current.Web.Url);
_seatCharts = _dc.GetList<Seating_chartItem>("seating_chart");
_users = _dc.GetList<UsersItem>("users");
_exusers = _dc.GetList<Excluded_usersItem>("excluded_users");
_rooms = _dc.GetList<RoomsItem>("rooms");
_logs = _dc.GetList<LogsItem>("logs");`

Main code:

try
{
    //  - - - - -   L O A D   T H E   * P E O P L E *   - - - - -

    // Create List objects
    List<Seating_chartItem> seatList = (from seat in _seatCharts where seat.Room == 0 where seat.Floor == floor select seat).ToList();
    List<UsersItem> usersList = (from user in _users select user).ToList();
    var xusersList = (from xuser in _exusers select xuser.User_id).ToList();
    usersList = usersList.Where(user => !xusersList.Contains(user.User_id)).ToList();

    // Query and use anonymous object for values
    var results = from seat in seatList
                  join user in usersList on
                  seat.User_id equals user.User_id
                  select new
                             {
                                 sid = seat.Seat_id,
                                 icon = seat.Icon,
                                 topCoord = seat.Top_coord,
                                 leftCoord = seat.Left_coord,
                                 name = user.Name,
                                 phone = user.Phone,
                                 mobile = user.Mobile,
                                 content = seat.Content
                             };

    results = results.Take(5);
    foreach (var r in results)
    {
        ImageButton img = new ImageButton();
        img.ID = "seat-" + r.sid;
        img.ImageUrl = "http://cxsmoss/rooms/" + r.icon;
        img.Style.Add(HtmlTextWriterStyle.Position, "absolute");
        img.Style.Add(HtmlTextWriterStyle.Top, r.topCoord + "px");
        img.Style.Add(HtmlTextWriterStyle.Left, r.leftCoord + "px");
        if (r.name == "")
            img.ToolTip = "no name!";
        else
            img.ToolTip = r.name;
        if (r.phone != "")
        {
            string phn = r.phone;
            if (phn.StartsWith("971")) // Comment this line
            {
                string extension = phn.Substring(phn.Length - 4, 4); //Comment this line
                img.ToolTip += Environment.NewLine + "x" + extension;

            }
            else
                img.ToolTip += Environment.NewLine + "x" + phn;
        }
        if (r.mobile != "")
            img.ToolTip += Environment.NewLine + "mobile:  " + r.mobile;
        img.ToolTip += Environment.NewLine + "room/cubicle: " + r.content.ToLower().Replace("seat ", "");
        img.PostBackUrl = ""; // "Default.aspx?name=" + row["name"].ToString();
        img.OnClientClick = "UpdateEmployeeInfo('" + r.name.ToString() + "', '" + img.ID + "');return false;";
        // For debugging size
        img.ToolTip += Environment.NewLine + "Results size " + results.Count();
        floorPanel.Controls.Add(img);
    }


    //  - - - - -   L O A D   T H E   * R O O M S *   - - - - -

    List<Seating_chartItem> seatListRooms = (from seatRoom in _seatCharts where seatRoom.Room == 1 where seatRoom.Floor == floor select seatRoom).ToList();
    List<RoomsItem> roomsList = (from room in _rooms select room).ToList();

    // Query and use anonymous object for values
    var res = from seatRoom in seatListRooms
              join room in roomsList on
              seatRoom.Seat_id equals room.Room_id
              select new
              {
                  rid = room.Room_id,
                  name = room.Name,
                  icon = seatRoom.Icon,
                  topCoord = seatRoom.Top_coord,
                  leftCoord = seatRoom.Left_coord,
                  phone = room.Phone,
                  content = seatRoom.Content
              };

    foreach (var s in res)
    {
        ImageButton img = new ImageButton();
        img.ID = "room-" + s.rid;
        //img.ID = row["icon"].ToString();
        img.ImageUrl = "http://cxsmoss/rooms/" + s.icon;
        img.Style.Add(HtmlTextWriterStyle.Position, "absolute");
        img.Style.Add(HtmlTextWriterStyle.Top, s.topCoord + "px");
        img.Style.Add(HtmlTextWriterStyle.Left, s.leftCoord + "px");
        img.ToolTip = s.name;
        if (s.phone != "")
            img.ToolTip += Environment.NewLine + "x" + s.phone;
        img.ToolTip += Environment.NewLine + "room " + s.content;
        img.OnClientClick = "UpdateRoomInfo('" + s.name + "', '" + img.ID + "');return false;";
        img.ToolTip += Environment.NewLine + "Res size " + results.Count();
        floorPanel.Controls.Add(img);
    }
}

If I comment out:

if (phn.StartsWith("971"))

and

string extension = phn.Substring(phn.Length - 4, 4);

everything runs fine. If I leave them in it only completes the first foreach. I have tried renaming all of the variables in the second query, explicitly casting r.phone to string and placing ToArray on the end of the results query. None of these helped.

Interestingly, if I use results = results.Take(5); to just walk through a few I get the rooms. Checking for the count of results and the count of res (the results of the second query) they are both the same - 5.

How can I reset everything so I can query my lists again?

Is it possible that phn is null?

Try replacing r.phone != "" with string.IsNullOrEmpty(r.phone) and/or turn on first chance exceptions in your debugger. (Debug->Exceptions-> Common Language Runtime Exceptions [check])