I2C LCD screen not working DFR0063

I can't get this display to work (DFR0063). All I get is a bunch of squares. I am just using the hello world code provided on the site.
I tried with a io shield, and straight on the A4 and A5 pins on an arduino uno with the same results. Can someone help?
I played with the contrast screw. It's not that.
I tried with a io shield, and straight on the A4 and A5 pins on an arduino uno with the same results. Can someone help?
I played with the contrast screw. It's not that.
