This scam was tried on me as well.
November 26th at Port Atlantis by both "Sweet Entropia Heart" and "Paris xxPHxx Hilton". They blamed the money disappearing from the trade window on the lag. One time I did press the trade button at the right moment, but Paris did not confirm the trade (though claiming she did).
So, watch out for these two! and others... They try to hurry you and blaim errors on their side on the lag.