What hub are you using? e.g. Gekko-science hub is very good for this purpose, due to the way its build. Chinese brand hubs are often causing problems.
What powersupply are you using? single rail 12V is very much advised, or an HP server powersupply.
Are you using cooling? newpac's are very sensitive to temperature. Slight moving of are is enough @ 100 Mhz, higher freq need more intensive cooling.
Also make sure your USB cable is of good quality.
See also previous pages, maybe a solution there.
Can you post your setup? Hardware, OS, HUB, PS, cooling.
My 1st thought is you're having a problem with hub and/or powersupply.
Q. Something doesn't look correct..
Here are some of the more common ways to address issue(s):
Isolate to test only the usb stick
Remove any usb extension cables.
Try a single device without any other accessories drawing power (usb fan, other miners).
Plug into a into different computer.
Check for and git the latest build of cgminer.
Look through the README.txt file for relevant notes.
Handling problems in Windows:
Switch to linux Ubuntu or Raspbian.
Enable High Performance in Power Options Setting.
Confirm the WinUSB driver is attached to the device.
Reboot the computer.
Try one cgminer process per device with "--usb :1".
Search for / post the details to this thread.
See first page for the above.