[libvirt] Can't run vbox's network driver and storage driver.

Hi, I just can't find a way running the network driver and storage driver provided by vbox. When I use vbox:///session as an url to run vbox driver and call network (or storage) API, the vbox's driver didn't execute. Instead, it would run drivers in src/network and src/storage. The problem only comes with the network driver and storage driver. Which means the vbox's domain driver works well with libvirt. I know that actually libvirt communicate with vbox driver though the remote driver, but I don't know how to make remote driver call vbox's network driver(or storage driver). BTW, I need vbox's driver because I have to do some test on it. Thanks, Taowei