Open Question: GTA Races…?

Okay, here's the deal. I have completed the main story mode of GTA IV and I am now going or the races that Brucie gives you, I have done most of them, apart from North and South Alderny. Whenever I phone Brucie to ask for a race, he says that there are no races going on. This has happened to me before, and after a few hours, there were races again. The problem is that I have let many days pass in the game, and he still says that there are no races, how do I get round this problem? Thanks in advance for any help