Thanks for the further info guys.

@Tabsoft - it's a 4 line 20 chr back lit display. I use them in all my projects and like I mentioned, works fine on the development board do something is screwed on the board, something that is taking the lines high or low and stopping the signals getting through.

I've traced out the schematic and compared it to the board and there are quite a few mistakes, not with the LCD part as that pings out but some nets were missed in the PCB layout module when the schematic was converted, but this was with a custom part, so that might of been human error on my part. I'm going to redraw the schematic, and re-work the PCB layout and check everything three times before sending the gerbers off. Still I have some posh new green and white coasters to put my cup of tea on so I guess all was not wasted

Thanks again for every ones contributions