应用程序通过ReadFile与驱动程序通信问题

驱动的IRP_MJ_READ例程中如下
PVOID str="From DDK!";
PIO_STACK_LOCATION stack = IoGetCurrentIrpStackLocation(Irp);
NTSTATUS status = STATUS_SUCCESS;
Irp->IoStatus.Information = 0;
RtlCopyMemory(Irp->AssociatedIrp.SystemBuffer,str,10);
Irp->IoStatus.Status = status;
IoCompleteRequest(Irp, IO_NO_INCREMENT);
 return status;

应用程序中
char myBuffer[1024];
HANDLE fh = CreateFile("\\\\.\\jwtDDKtest",
            GENERIC_READ | GENERIC_WRITE, 0, NULL,
            OPEN_EXISTING, 0, NULL);
ReadFile(fh,myBuffer,10,&t,NULL);
CloseHandle(fh);
请问为什么应用程序中读不到驱动中的From DDK!呢