only two of the four queues work on the VF interface of Intel X553 nic.

Hi all,
        I encounter a problem that there are two of the four queues working
for dpdk-apps when using the VF interface of intel x553 10G-ethernet NIC.
Straightly speaking, there are no packets coming into the last two queues,
no matter what packets I send to the dpdk-apps.
        I checked the initialization of the queues,  it shows  that all
four queues are initialized successfully.
        If I use the PF directly for dpdk-apps, there is no such problem.
        If I missed some configuration when using the VF ?
        if so, what should I do ?

        I am appreciate to get some  discussion from you.