Adc Pic

i am using CCS C... what should i do to make my portA to ADC port...what should i write in my program ? i am using PIC18F4550

setup_adc_ports(ALL_ANALOG);
setup_adc(ADC_CLOCK_DIV_64);
setup_psp(PSP_DISABLED);
setup_spi(FALSE);
setup_timer_0(RTCC_INTERNAL|RTCC_DIV_1);
setup_timer_1(T1_INTERNAL|T1_DIV_BY_1);
setup_timer_2(T2_DISABLED,0,1);
setup_comparator(NC_NC_NC_NC);
setup_vref(FALSE);

lcd_init();
lcd_gotoxy(1,1);
lcd_putc("Hello World");

i use this before lcd display.. and it cant work... but i put after it..it works... is the code correct?