Usb connection requirements for BeagleBone Black

Hello there,
I have a question regarding usb slave connection to BeagleBone Black. I have designed a system where I connect the D+ and D- wire from mini usb B connector of the BeagleBone Black to the shield board and from there it is put out on a USB B connector (GND too). The problem is the PC doesnt see BeagleBone Black when connecting through that USB. I was wondering- does BeagleBone Black need to see the VCC from USB to know that usb was connected? If yes, this is unconvinient for me, because I would like to prevent BeagleBone Black to be powered through USB. I am able to get a workaround for this using external components but I wonder if this is the case. I would aprichiate any help.

I have tested it actuially, for a proper USB enumeration the USB0_VBUS has to be applied.