LCD screen not displaying text with Arduino NANO?

I'm using this tutorial:

I've used a voltage measure thing on the potentiometer and the readings don't change when I turn the potentiometer etc.

Perhaps there's something wrong with my wiring? I've tried the exact same wiring on an Arduino UNO board and that still doesn't work! I've also tried a different potentiometer to the pictured one and still the same problem. Thanks.

Thanks.

The power strips along the edge of the breadboard do not join in the middle. Look at the red and blue stripe and you will see where the break is. Add jumpers to join the strips.

Omg thank you so much! I thought the strips were all connected together throughout