PLW1000v2 -- WiFi installation in existing network.

I purchaced a NetGear PLW1000v2 WiFi extender, which included a PL1000v2 network adapter.   I want to add the WiFi extender to my existing network of 3 PL1000's

    Out of the box, the two items connected.  (From what I remember)

    I pressed the security button on one of the 3 existing adaptors and the power LED begins blinking.   I then press the security button on the new WiFi adaptor and it does not add itself to the network.

   I can press the security button of any of the 3 existing adaptors correct?

   Also, the power LED blinks endlessly on the new adaptor when I initiate the security button push from it.  That seems wrong.

   Any help would be appriciated.   I don't want to pack it up and send it back.

   Note:  It is a refurbished item from Amazon.

Thanks.