Trouble connecting multiple drives to Airport Extreme

I am trying to connect 3 external hard drives (2 of them are one partition only, and one is partitioned into two partitions) through a USB hub to my Airport Extreme, and only one drive and one partition of the split drive are showing up. To rule out the USB hub, we connected each drive to the Airport Extreme directly, and still only the drives that showed up through the USB hub showed up when connected directly. The others show up in Airport Utility as drives, including the drive in 2 partitions, but are not accessible by any means I know. Please help. Thanks.

I have only seen Network drives in multiples on an AEBS using the ethernet ports and Time Machine on the USB.

How are the drives formatted? Is the one partiton HFS+ - I think every time I hooked up a drive to AEBS/Time Capsule I had to format it HFS+ for it to find it.