Problem in adc while programing in lpc21xx

#include <lpc213x.h>
#include "usart0.c"

int main()
{
	unsigned int data;
	usart0_init();
	usart0_char('a');
	PINSEL1 |= 0X01000000;			//SET THE FUNCTION FOR PORT PIN AS ADC FOR ADC0.1
	AD0CR = 0X00000002;				//SELECT ADC0.1 CHANNEL
	AD0CR |= 0X00000200;				//SELECT THE CLKDIV(division factor) AS 2 i.e, 12/(2+1) = 4MHz
	AD0CR |= (~(1<<16));				//SET BURST AS 0
	AD0CR |= 0X00000000;				//NO. OF CLOCKS = 11 (CLKS = 000)
	AD0CR |= (1<<21);						//SET A/D IN OPERATIONAL MODE (PDN = 1)
	
	
	while(1)
	{
		AD0CR |= (1<<24);
		//ADGSR |= (1<<24);
		while(!(AD0DR1 & 0x80000000));
		data = AD0DR1 & 0X0000FFC0;
		data = data>>6;
		usart0_char(data);
		//AD0CR |= (~(1<<24));
		//ADGSR |= (~(1<<24));
	}
}

#define Fosc            12000000                    
#define Fcclk           (Fosc * 5)                  
#define Fcco            (Fcclk * 4)                 
#define Fpclk           (Fcclk / 4) * 1             

#define  UART_BPS	9600	

//void UART0_RXC() __irq;

void usart0_init()
{
	//unsigned char temp;
	unsigned int Baud16;
	PINSEL0 = 0X05;			// selecting P0.0 & P0.1 for usart0 function
	U0FCR = 7;								// clear FIFO, transmit & recieve enable
	U0LCR = 0X83;							//DLAB = 1, stopbits =1, data length = 8bit
	Baud16 = (Fpclk / 16) / UART_BPS;  
  U0DLM = Baud16 / 256;							
  U0DLL = Baud16 % 256;							
	U0LCR = 0X03;							// clearing DLAB bit
// 	U0IER = 0x0001;
// 	dummy = U0IIR;
// 	VICIntSelect=0x00000000;
// 	VICIntEnable=0x00000040;
// 	VICVectCntl0=0x20|6;
// 	VICVectAddr0=(unsigned long) UART0_RXC;
}


void usart0_string(unsigned char *data)
{
 	while(*data)							// transmit only
	{
		U0THR = *data;
		while(!(U0LSR & 0X20));
		data++;
	}
}	



// 	{
// 		while (!(U0LSR & 0x01)); //receive and transmit
// 		temp = U0RBR;

void usart0_char(unsigned char temp)
{
 		U0THR = temp;
 		while(!(U0LSR & 0X20));	
}

// void UART0_RXC() __irq
// {
// 		unsigned char temp;	
// 		U0IER = 0x0000;
// 		temp = U0RBR;
// 		U0THR = temp;
// 		while(!(U0LSR & 0X20));
// 		U0IER = 0x0001;
// 		VICVectAddr = 0;
// }