ADC Read giving me 0!

ADC Read giving me 0!

my MCU is LPC1768

this is my code:
the library i wrote for adc

[CODE] #include "LPC17xx.H"

void adc_init()
{ LPC_SC->PCONP |= (1 << 12); //set PCADC for power on ADC ; LPC_ADC->ADCR |= (1 << 21); // start adc LPC_PINCON->PINSEL1 &= ~0x003FC000; /* P0.23~26, A0.0~3, function 01 */ LPC_PINCON->PINSEL1 |= 0x00154000; LPC_PINCON->PINMODE1 &= ~0x003FC000; LPC_PINCON->PINMODE1 |= 0x002A8000;
}

int ADCRead(char channelNum) {
int data; LPC_ADC->ADCR &= 0xFFFFFF00; // clear channels LPC_ADC->ADCR |= (1 << 24) | (1 << channelNum); // set chanel and start convert while (!(LPC_ADC->ADGDR & (1<<31))); //wait to done data = LPC_ADC->ADDR7; LPC_ADC->ADCR &= 0xF8FFFFFF; /* stop ADC now */

data = ( data >> 4 ) & 0xFFF; return ( data ); /* return A/D conversion value */
} [/CODE]

[CODE]#include <br> #include <br> #include "uart.h"
#include "adc.h"

void Delay (uint32_t Time)
{ uint32_t i;

i = 0; while (Time--) { for (i = 0; i < 5000; i++); }
}

int main(void)
{ volatile int i=0; unsigned char lcd_buf[32];

SystemInit(); adc_init(); UART0_Init();

while (1) { i++; sprintf(lcd_buf,"AnalogRead(%d)(A0): %d\r\n\n",i,ADCRead(0)); UART0_SendString(lcd_buf); Delay(2000); }
}[/CODE]

it just keeps returning 0!!!!