Interfacing ADS8513 ADC with PIC18F45k20

sbit Conversion_Select at RC1_bit;
sbit Conversion_Select_Direction at TRISC1_bit;
sbit Slave_Select at RA5_bit;
sbit Slave_Select_Direction at TRISA5_bit;

// LCD module connections (pinout settings)
sbit LCD_RS at RD2_bit;
sbit LCD_EN at RD3_bit;
sbit LCD_D4 at RD4_bit;
sbit LCD_D5 at RD5_bit;
sbit LCD_D6 at RD6_bit;
sbit LCD_D7 at RD7_bit;

// LCD pin direction
sbit LCD_RS_Direction at TRISD2_bit;
sbit LCD_EN_Direction at TRISD3_bit;
sbit LCD_D4_Direction at TRISD4_bit;
sbit LCD_D5_Direction at TRISD5_bit;
sbit LCD_D6_Direction at TRISD6_bit;
sbit LCD_D7_Direction at TRISD7_bit;

void Init_Main()
{
    Slave_Select=1;
    Slave_Select_Direction=1;
    Conversion_Select=0;
    Conversion_Select_Direction=0;
    SPI1_Init_Advanced(_SPI_SLAVE_SS_ENABLE,_SPI_DATA_SAMPLE_MIDDLE,_SPI_CLK_IDLE_LOW,_SPI_HIGH_2_LOW);
}
unsigned char SPI_Read1()
{
    SSPBUF=0xff;        /* Copy flush data in SSBUF */
    while(!PIR1.SSPIF);    /* Wait for complete 1 byte transmission */
    PIR1.SSPIF=0;        /* Clear SSPIF flag */
    return(SSPBUF);        /* Return received data.*/
}
short ADC_Value ()
{
    short take, buffer;
    Conversion_Select=1;
    Delay_us(10);
    Conversion_Select=0;
    take=SPI_Read1();
    buffer= (take) & 0x0000;
    buffer= (buffer << 8);
    take=SPI_Read1();
    buffer = (buffer) & (take);
    return (buffer);
}

void main()
{
    char txt[16];
    short i;
    ANSEL  = 0;                           
    ANSELH = 0;
    Init_Main();
    Lcd_Init();
    Lcd_Cmd(_LCD_CLEAR);                   
    Lcd_Cmd(_LCD_CURSOR_OFF);             

    while(1)
    {
     i = ADC_Value();
     ShortToStr(i,txt);
     Lcd_Out(1,5,"ADC test");
     Lcd_Out(2,1,txt);
    }
}

take=SPI_Read1();
    buffer= (take) & 0x0000;     --> gives 0 !
    buffer= (buffer << 8);
    take=SPI_Read1();
    buffer = (buffer) & (take);
    return (buffer);

    take=SPI_Read1();
    buffer= (take<< 8);
    take=SPI_Read1();
    buffer = buffer + (take& 0x00FF) ;
    return (buffer);