Security Settings For Wireless Repeating Function

I want to add another router to extend the range of the WND3400. When going to the wireless repeating function and clicking on "Enable Wireless Repeating Function", a message pops up that says that WPA-PSK, WPAs-PSK & WPA-PSK + WPA2-PSK are not available to use with wireless repeating and to change that. The only other security option I have is NONE, which does not sound right that I should choose that. Does this make sense? How can I have the WND3400 as the base station with no security? Thanks for your help.