ADS131E08S: ADS131E08S with PIC18F26K22 Data reading issue

I am using ADS131E08S with PIC18f26k22 for reading Force sensor values. The sensor which i am using is FSG020WNPB. 

These are my register settings,

CONFIG1         0xF2

CONFIG2         0xE0

CONFIG3         0xE8

CH1SET          0x20

After initialization of registers using below code i am reading values from ADC and printing it on the terminal.

************************************************************************************************************************************************

CS = 0;
PORTCbits.RC0 = 1; //start pin making high
spiwritecommand(ADC_START_CMD);
CS = 1;

CLOCK = 0;
__delay_us(10);
CLOCK = 1;

PORTCbits.RC1 = 1; //making DRDY pin as low

//as per Data sheet Issue this command after DRDY goes low to read the conversion result
CS = 0;
spiwritecommand(ADC_READ_DATA_CMD);
CS = 1;

char pri[15];
int x;
CS = 0;
for(x=0;x<27;x++)
{
adcArray[adcArrayIndex] = spi_write(0x00);
adcArrayIndex++;
}
CS = 1;
adcvalue1 = Parse_24bit_adc_values(CHANNEL1_INDEX);
sprintf(pri,"%ld",adcvalue1);

sendResponseViaUart(pri);
uartWriteByte(0x0D);
PORTCbits.RC0 = 0;

*******************************************************************************************************************************************************

i am converting the Values read by ADC into voltage by using below equation,

voltage = ADC value * Vref / ADC resolution

where Vref = 2.4V

these are the values and corresponding voltages i am getting, while applying force on the Force sensor

ADC value                                                   Voltage

I have tried connecting a potentiometer to the channel 1 and applied a fixed voltage 

Everytime the values are keep on changing. Even if applied any fixed voltage also the values(Read by ADC) s changing.

Kindly advice how to proceed further.