FYI, front usb ports fail to see or install devices sometimes. (due to a lack of available power to it)
The ones on the back (if it's a tower) have better power.
If that doesn't do it then go to device manager and see if it will detect by telling the computer to "find new hardware" and/or see if it is detected already by watching the device manager screen while you plug it in or unplug it. (driver might not be installing even though the computer see's it as being there.)
If neither of these work, and the usb port you are using works with other usb devices then the dongle is bad.