Q: I can't pair my keyboard to window 7 after re-install window

Previously, i can use my keyboard with both osx and window. After I decided to re-install window 7

and reinstall bootcamp from apple website. It cannot pair in window but still work in osx. I can add my keyboard but it is not working.

I think it is driver problem but i don't know how to fix it. I already install bootcamp.

thank for help

iMac27" late 2012 , osx el capitan , window7