I have a USB NTFS drive hooked up to my Mac Mini. I want to share it on the network so my MBP can write to the USB drive. When I share the drive in OSX, the Users box is grayed out, so I can't add users or change permissions. I can connect to it from my MBP but I can't write files without permissions I tried AFP and SMB. Is the problem the NTFS or the fact that it's a USB drive? Any other way I could write to it from the network?