irp_mj_create dispatch function doesn\'t work if the driver is loaded on demand,why?

as title, I write a filter driver with a IRP_MJ_CREATE dispatch function to
intercept some operations. If the driver is loaded on boot, the function
works well, but if loaded on demand after system boot,it does nothing, even
I put a breakpoint in the function using softice, I can not step into the
function because the breakpoint never stop the execution.

你能确定attach到volume device上了吗