Initially had the wiring backwards, were connected the line wires to the load terminals, and the load wires to the line terminals. Didn’t work. Watching the video helped to reverse the wires, then it worked like a charm. The most challenging part is determining the two white wires, which of them is the load and which is the line. One of the black wires is the hot/line wire, it’s easy to test that with a voltage tester, and the other black is going to be the load wire. One black wire is the hot wire, one black wire is the load wire. There also two white wires. One of them is the load wire and the other one is the line wire that is coming from the other receptacle. In my case the other receptacle (regular outlet receptacles) is located in the backyard and this GFCI receptacle is located in the garage. Every time was raining, the GFCI receptacle was tripping. So I end up replacing both, since both of them already served for 13 years. But only the outside receptacle was bad. But with the installation of the new receptacle I added an additional waterproof cover. If you can see the white wires end inside the outlet box, the load wire usually is bundled up with the other white neutral/load wires. But if you can’t see the end of the white wire, most likely that’s the line wire coming from the other receptacle. Even if you do make the connection wrong, just reverse the white wires and that should correct the connection. Assuming that you already have identified the two black wires, which one of them is the hot wire and the other one is the load wire. In my application, there are of 4 wires plus the ground bare copper wire. 1) Two wires are the load wires (one is white and one is black) 2) Two wires are Line wires (one is white and one is black) 3) Two “line wires” connects to the “line terminals”, and “two load” wires connect to the “load terminals”. As I mentioned, once you have identified which white wire is the line wire that is coming from the other receptacle, the other white wire is going to be the load wire. And in most cases the load wire is going to be bundled up with the other white wires in the outlet electrical box, connected with a short piece of white wire. If you can see this short white wire, then you should know that is the load wire to be connected to the load terminal. Both white wires connect to the chrome terminal screws and both black wires connect to the brass terminal screws. However one black wire is the hot wire, the other black wire is the load wire. Likewise one white wire is the Line wire and the other white wire is the load wire. Before the wiring, the white wires are the neutral wires and the black wires are the hot/line wire and a load wire. Also in a different application, the black load and white load wires can be referred to as the traveler wires, since they are coming from the other outlet. Mostly that applies to the 2, 3, 4 way light switches installation. Don’t get electrified! Turn off the power at the switch breaker before start any electrical work!