I found the solution.
https://www.mail-archive.com/vbox-dev@virtualbox.org/msg06254.html
If virtualbox is installed in the Windows8.1, I cannot see the "add a wireless display" icon in Windows8.1.
So I removed virtualbox and re-install without Virtualbox bridged networking.
After doing it, I can see the "add a wireless display" icon.
Could you tell me why this problem is happened when installing VirtualBox with the bridged networking(it's default install option)?
Thank you.
Kyungnam.