WKB-4000us USB WiFi Keyboard Does Not Work

The WKB-4000us model keyboard I have has no sync button on the keyboard itself but it does have one on the USB Receiver stick.

        

 

  

I held down the FN key on the keyboard while pushing the connect sync button on the
USB Receiver at least 3 times.

Also Try To Unpair use Fn Key and Num Lock key then try to pair it again.

Found a copy of the instructions see Dropbox link below

https://www.dropbox.com/s/vkzciz1u1rbd77u/WKB-4000.pdf?dl=0

instructions say

"Within 15 seconds of pressing the “SW” button press the “Fn” key on the lower left corner of the wireless keyboard".