The question is clear enough.. I just don't understand why you are having issues.
Can you see in the internal disk of the TC in the finder?
What format are you using on this disk? Try and format it HFS+ if it isn't already.
If you plug it directly into the Mac it works ok??
The other issue is the need for a powered hub on the TC due to the low power it gives the internal port.. or lack of bios compatibility with a range of usb hub chips. Try a powered hub as that can also help.