弱问:驱动程序返回不了给定数据

Test(PIRP irp)
{
    USHORT val;
    val=14;
    PIO_STACK_LOCATION irpStack = IoGetCurrentIrpStackLocation( irp );
    ULONG dwInputLength = irpStack->Parameters.DeviceIoControl.InputBufferLength;
    ULONG dwOutputLength= irpStack->Parameters.DeviceIoControl.OutputBufferLength;


    PVOID p = ExAllocatePoolWithQuota(NonPagedPoolCacheAligned, 2);


    RtlCopyMemory(p, &val, 2);
    irp->AssociatedIrp.SystemBuffer=p;
    return CompleteIrp(irp,0,2);}

CompleteIrp( PIRP Irp, NTSTATUS status, ULONG info)
{
    Irp->IoStatus.Status = status;
    Irp->IoStatus.Information = info;        // return byte information
    IoCompleteRequest(Irp,IO_NO_INCREMENT);
    return status;
}

为什么应用程序端接收不到我给定的数据呢?
各位大侠,请指教