为什么Application_Start在卡西尼而不在IIS7中运行?

I have an ASP.NET 3.5 sp1 app that's in development in Cassini. The app includes a global.asax file that should run some code - it works fine in Cassini but in IIS the debugger never hits the function. Why doesn't that code run?I have an ASP.NET 3.5 sp1 app that's in develop