Bad plot - a fixable flaw!
Something occured to me when watching this again... the reason why it doesn't make sense is that a major scene was edited into the wrong place! James Bond talks Vesper into recruiting Evelyn Tremble shortly after returning to the Secret Service, which makes no sense, especially considering this plot line doesn't pick up until much later, when Evelyn punches the airport employee.
This was an editing mistake - the sequence that was meant to follow the training of Cooper (which is pretty much unimportant to the film anyway) is James's journey to meet Mata Bond, and her time at the spy school. Hence, when the auction falls through, Le Chiffre says that he'll get the money through baccarat, AFTER which Bond was supposed to visit Vesper concerning Evelyn. So if you have some patience and a half-decent editing program, it's actually possible to make this movie have a reasonable plot!