Vilros Starter Kit Circuit #11

The goal of this circuit is to get two LED’s to flash interchangeably. There is a relay, but it needs a transistor to drive the switching.

I can’t seem to figure out what is wrong with my setup. I have torn it down and rebuilt it according to the book 3 times. I’ve double checked that the relay is correctly oriented. 1 LED lights up, but the relay fails to switch. I think there is a problem with the transistor maybe? How can I tell if I have a shoddy transistor? Also, when I plug it into the computer, the computer makes the “USB Unplugged” sound over and over again about every second, but the LED remains lit. I’m not sure what that means.

Thanks for looking. I could really use some help!

I looked on another forum and apparently the setup works if you switch the direction of the diode from how it's shown in the book. I tried this and it works.