Printing via USB and HUB.

Hi,
If anyone knows the solution to the problem?

I have ICY BOX IB-NAS4210-B with Linux OS (ARM). There's a print
server and 1 USB port for printer.
I plug the printer 1 to the USB port and print server prints Ok.
I plug the printer 2 to the USB port and print server prints Ok.
I plug the printer 3 to the USB port and print server prints Ok.
Ok.
Now I plug the printer instead of USB 2.0 Hub to the print server and
plug every 3 printers into the HUB.
NAS sees the hub and only one (Lexmark e250d) printer and can not see
the other printers (i think having USB v1 interfaces).
HUB is Ok because when I connect it to Windows XP, each of the printer
is ready to print and prints (3 printers plugged at once).
If you know how to solve this, please share with me the knowledge.