You could try the following...

Firstly since the R/W line is connected you should define it along with the other LCD defines...

DEFINE LCD_RWREG PORTA
DEFINE LCD_RWBIT 2

Secondly, as in most PIC's with multiplexed Analogue inputs on PortA, the default on power-up for RA0, 1, 2, 3 and 5 is Analogue mode. You need to switch those pins to Digital mode. Add this statement along with your TRISA etc...

ADCON1=$07

See section 17 of the 18F452's Datasheet for an explaination of what I've done.

Hopefully that will get you up and running.

Melanie