LPC2148 ADC working but incorrectly

hey

i am using LPC 2148. and configured the hardware for taking the analog signal at P0.28 which is ADC0 channel 1.

i am using following code but the output stays 0 or 1023 only.

my hardware connections are verified with several ready made boards and kits for the same controller..

kindly check and help for my problem..

thanks

#include<lpc214x.h>
#include<stdio.h>


//VPB clock 30Mhz
void delay(int);

extern long val,stat,s;
extern long adc_val;


int main()
{
        serial_init();
        clear_arrays();
        adc_init();
        //printf("MISSAR SYSTEMS\n\n");

        while(1)
        {

                adc_read();
                printf("%i\n",adc_val);
                delay(1000);
        }
}

void adc_init(void)
{
        PINSEL1 = 0x01000000;   // P0.28 - AD0.1
        PCONP |= 0x00001000;
        AD0CR &= 0x00000000;
        AD0CR |= 0x00201302; // with clock = PCLK/(7+1) = 30Mhz/8 = 3.75Mhz
        AD0INTEN &= 0x00000000;

}

void adc_read(void)
{
        AD0CR |= 0x01000000;    // Start AD conversion NOW on AD0.1 (P0.28)
        delay(100);
        do
        {
                val = AD0DR1;    // Get value
        } while ((val & 0x80000000) == 0);  // until bit 31 is high (DONE)

        val = (val>>6);
        adc_val = val & 0x3FF;       // Extract AD result
}

void delay(int delay_value)
{
        int out_delay=0,in_delay=0;

        for(out_delay=0 ; out_delay < delay_value ; out_delay++)
        {
                for(in_delay=0 ; in_delay <= 1000 ; in_delay++);
        }
}