How to connect wires to this connector

I am installing an undercabinet light and have to connect the supply neutral and live wires (14AWG) to this connector. I have never seen this connector before and am stumped about how to use this. I have tried pressing those tabs on the top (which seem like spring loaded) and inserting the wires and letting go. Inserting the wires and then pressing the tabs but nothing seems to work. Would appreciate suggestions from the experts here. 

https://preview.redd.it/aqjkelomovng1.jpg?width=4032&format=pjpg&auto=webp&s=81b1f5b673ef5cbb108135eb79838eb2c2882398