Linq query String.Format

I am stuck on a wierd problem. I have a CashGameGeneralViewModel class wich looks like this

public class CashGameGeneralViewModel
{
    public string Limit { get; set; }
    public int HandsPlayed { get; set; }

    public float AmountWon { get; set; }
}

Here is the method that should return all hands played by a certain player:

public List<CashGameGeneralViewModel> GetAllHands(string playerToFind)
    {
        HoldemHandContext db = new HoldemHandContext();
        int playerId = GetPlayerId(playerToFind);
        var holdemHandResult = (from phh in db.PlayersInHoldemHands
                                from hh in db.HoldemHands
                                where hh.Id == phh.HandPlayed && phh.PlayerId == playerId
                                select new CashGameGeneralViewModel()
                                           {
                                               Limit = //"some text",
                                               String.Format("{0:0.00}", hh.SBlindAmount) + "/" +
                                               String.Format("{0:0.00}", hh.BBlindAmount),
                                               HandsPlayed = db.HoldemHands.Distinct().Count(),
                                               AmountWon = 0
                                           }
                                ).ToList();

        return holdemHandResult;
    }

    public int GetPlayerId(string playerToFind)
    {
        HoldemHandContext db = new HoldemHandContext();
        int playerId = (from p in db.Players
                        where p.ScreenName == playerToFind
                        select p.Id).FirstOrDefault();

        return playerId;
    }

The problem now is the

Limit = //"some text",
String.Format("{0:0.00}", hh.SBlindAmount) + "/" +
String.Format("{0:0.00}", hh.BBlindAmount)

part. hh.SBlindAmount and hh.BBlindAmount are float values. I wanted to use String.Format because 0.10 is shortened to 0.1 and with the string format I got it like i want it. But I am getting an exception wich says 'The invocation of the constructor on type 'PokerRecord.View.CashGameGeneralUC' that matches the specified binding constraints threw an exception.' Line number '60' and line position '18'.. When I remove the string.format and put in some "regular" string everything works fine... Anyone knows why?