Where in your network are you connecting the kit?
Are you, for example, going:
Modem ----> Ethernet cable ----->unit 1 (in wall outlet) < ==== electrical circuit====> (wall outlet) Unit 2 ---Ethernet cable ---->-[LAN]router
Normally the first unit is between the router [LAN port] and a wall outlet. The second unit is plugged into another wall outlet (on the same circuit) with an Ethernet cable going to the connected Ethernet device; computer, switch, printer, etc..
No power strips or extension cords - just the outlets.
Also check the User Guide/Manual. Sometimes it takes the units a few minutes to find each other and pair up if that is happening at all. The User Guide/Manual should explain the LED (lights) that show if connectivity is in place.
Follow the instructions very carefully. Make sure that the units are correctly installed.
And remember that if the electrical circuit is not good - the powerline adapters may not work.