Setting WDS function of WNDR4300

Hi,

Now I'm trying to use my two 4300s as a WDS base station and  a repeater respectively in the 5GHz band, and I'm having  trouble setting up the repeater.  (Setting up the base station is ok.)

Starting on page 96 of the user's manual below,  I think I'm certainly following the instructions in this manual:

https://www.downloads.netgear.com/files/GDC/WNDR4300/WNDR4300v1_UM_30Oct2015.pdf

 But I  can't select the "Wireless Repeater" radio button in almost every trial. Even If I could, next I can't fill in the "Repeater IP Address" field nor the "Base Stasion MAC Adress" field, because they are still grayed out. 

I'm trying it with English UI and Japanese UI of version 1.0.1.60 firmware. (The latter is my native language.)

Are there any instructions that I must follow other than of the manual? Or actually the repeater function isn't available in this version of firmware? 

I would appreciate any information or suggestion about it.

Thank you for your help,
Susie B.