Grub is not showing after install debian on windows 8.1 laptop

["丁海江" <394087000@qq.com>]

I tried to install debian whizzey into my laptop which runs windows 8.1 now, and the last step i have chosen to install grub with mbr.

Then it asked me to reboot, after reboot, there is no grub and directly launching the windows as normal.

Can anyone help?

How can i get the grub to be shown before windows is showing?