Arduino on PCB

I wanted to make a circuit on a PCB, in which the Arduino (Atmega328) performs some functions (involving ADC & LCD).
The atmega is programed in the Arduino board itself and then transferred to the PCB.

Referring this http://itp.nyu.edu/physcomp/Tutorials/ArduinoBreadboard I built the circuit but my LCD is not working, I checked the connections and the coding (using the LCD Lib - 4 bit) and everything seems fine.

What could be wrong? The LCD works with the same connections and code on arduino board. Should I add some capacitors or is it something else?

Also in order to use the ADC, I should connect AVCC pin thru a Low Pass Filter...any suggestions for it, I have plenty of capacitors and some inductors too...

There's any number of possibilities that could be wrong. Post an image of your schematic, some picture(s) of your PCB (top and bottom), plus your code. It will help us to diagnose the problem better.

Maybe the Atmega328 is not even working but we never know if you don't provide some hi-res pictures and schematics.