Also,

Here is something else to look at, that frustrated me for a while.

Note on the specs that the Vo LCD voltage may be specified relative to the supply voltage (Vdd) and not ground.

Use a 20K pot wired as a voltage divider to feed the Vo and check that the output voltage is close to the spec. a 5k or 10k pot will work too.

On mine at least, there was a fairly narrow range, where the LCD was readable.

It turned out that mine was working all along, I just didn't know it.

Bob