During Xilinx ISE/LabTool installation the drivers for the platform cable should also be added to your system.
If this fails for any reason, the boundary scan will fail and Device Manager will show a yellow exclamation point next under Programming Tools or Unknown.
If this happens, please try reinstalling the drivers following the instructions at https://www.xilinx.com/support/answers/54381.html :
Disconnect the Xilinx USB cable. Alternatively, you can disabled the USB cable in the device manager first then re-enable them in step 5; in this case, you will not even need to reboot.
Open a Command Window (Start > then type cmd) as Administrator (right click > Run as Administrator)
Navigate to <Xilinx install>\bin\. This is usually c:\Xilinx\LabTools\LabTools\bin
Navigate to nt64 on a 64 bit system (usual) or nt on a 32 bit system.
Run wdreg -inf windrvr6.inf uninstall
Run wdreg -inf windrvr6.inf install
wdreg -inf xusbdrvr.inf uninstall
Run wdreg -inf xusbdrvr.inf install
Connect the Xilinx USB cable
Accept any installation prompts to accept Jungo cables or similar.