I don't know about G-LCD's but recenty I had an issue with an 2x16 LCD from Winstar.

All known LCD's I 've used up to this moment had the #1 pin as GND and #2 pin as Vdd. The Winstar has the power supply in the opposite order! So read the manuals and Data Sheet is still valid!

Also I used to ground the contrast pin as it was not necessary to adjust it. All LCD that I got this month need to be adjusted through a trimmer! And I did not put that thing on the PCB... :-(

Ioannis