SCP1000 datalogger (RTC Problems)

I’m using an Arduino Mini pro to read a Sparkfun SCP1000 pressure sensor and logging it to and openlog. I would like to add a time stamp to it, so I have added a DS1307 RTC into the mix.

My problem is that when the RTC ic connected I only get zeroes fron the the pressure sensor.

here is my code (a bit untidy at the moment since it was cut and shut from two different working codes for each of the devices.

// define spi bus pins
#define SLAVESELECT 10
#define SPICLOCK 13
#define DATAOUT 11      //MOSI
#define DATAIN 12       //MISO
#define UBLB(a,b)  ( ( (a) << 8) | (b) )
#define UBLB19(a,b) ( ( (a) << 16 ) | (b) )

#define REVID 0x00      //ASIC Revision Number
#define OPSTATUS 0x04   //Operation Status
#define STATUS 0x07     //ASIC Status
#define START 0x0A      //Constant Readings
#define PRESSURE 0x1F   //Pressure 3 MSB
#define PRESSURE_LSB 0x20 //Pressure 16 LSB
#define TEMP 0x21       //16 bit temp

char rev_in_byte;          
int temp_in;
unsigned long pressure_lsb;
unsigned long pressure_msb;
unsigned long temp_pressure;
unsigned long pressure;

#include "Wire.h"
#define DS1307_I2C_ADDRESS 0x68

// Convert normal decimal numbers to binary coded decimal
byte decToBcd(byte val)
  return ( (val/10*16) + (val%10) );

// Convert binary coded decimal to normal decimal numbers
byte bcdToDec(byte val)
  return ( (val/16*10) + (val%16) );
// Gets the date and time from the ds1307
void getDateDs1307(byte *second,
byte *minute,
byte *hour,
byte *dayOfWeek,
byte *dayOfMonth,
byte *month,
byte *year)
  // Reset the register pointer

  Wire.requestFrom(DS1307_I2C_ADDRESS, 7);

  // A few of these need masks because certain bits are control bits
  *second     = bcdToDec(Wire.receive() & 0x7f);
  *minute     = bcdToDec(Wire.receive());
  *hour       = bcdToDec(Wire.receive() & 0x3f);  // Need to change this if 12 hour am/pm
  *dayOfWeek  = bcdToDec(Wire.receive());
  *dayOfMonth = bcdToDec(Wire.receive());
  *month      = bcdToDec(Wire.receive());
  *year       = bcdToDec(Wire.receive());

void setup()
  byte clr;
  pinMode(DATAIN, INPUT);
  digitalWrite(SLAVESELECT,HIGH); //disable device  
  SPCR = B01010011; //MPIE=0, SPE=1 (on), DORD=0 (MSB first), MSTR=1 (master), CPOL=0 (clock idle when low), CPHA=0 (samples MOSI on rising edge), SPR1=0 & SPR0=0 (500kHz)
  byte second, minute, hour, dayOfWeek, dayOfMonth, month, year;

  Serial.println("Initialize High Speed Constant Reading Mode");

void loop()
  rev_in_byte = read_register(REVID);
  pressure_msb = read_register(PRESSURE);
  pressure_msb &= B00000111;
  pressure_lsb = read_register16(PRESSURE_LSB);
  pressure = UBLB19(pressure_msb, pressure_lsb);
  pressure /= 4;
  Serial.print("PRESSURE [");
  Serial.print(pressure, DEC);
  Serial.print(" Pa] ");
  temp_in = read_register16(TEMP);
  temp_in = temp_in / 2;
  //temp_in = ((1.8) *temp_in) + 32;
  Serial.print("TEMP [");
  Serial.print(temp_in / 10 , DEC); //displays whole part of number
  Serial.print(temp_in - ((temp_in / 10) * 10)); //displays decimal part of number
  Serial.print(" c] ");
  byte second, minute, hour, dayOfWeek, dayOfMonth, month, year;
  getDateDs1307(&second, &minute, &hour, &dayOfWeek, &dayOfMonth, &month, &year);
  Serial.print(hour, DEC);
  Serial.print(minute, DEC);
  Serial.print(second, DEC);
  Serial.print("  ");
  Serial.print(dayOfMonth, DEC);
  Serial.print(month, DEC);
  Serial.println(year, DEC);


char spi_transfer(volatile char data)
  SPDR = data;                    // Start the transmission
  while (!(SPSR & (1<<SPIF)))     // Wait for the end of the transmission
  return SPDR;                    // return the received byte

char read_register(char register_name)
    char in_byte;
    register_name <<= 2;
    register_name &= B11111100; //Read command
    digitalWrite(SLAVESELECT,LOW); //Select SPI Device
    spi_transfer(register_name); //Write byte to device
    in_byte = spi_transfer(0x00); //Send nothing, but we should get back the register value

unsigned long read_register16(char register_name)
    byte in_byte1;
    byte in_byte2;
    float in_word;
    register_name <<= 2;
    register_name &= B11111100; //Read command

    digitalWrite(SLAVESELECT,LOW); //Select SPI Device
    spi_transfer(register_name); //Write byte to device
    in_byte1 = spi_transfer(0x00);    
    in_byte2 = spi_transfer(0x00);
    in_word = UBLB(in_byte1,in_byte2);

void write_register(char register_name, char register_value)
    register_name <<= 2;
    register_name |= B00000010; //Write command

    digitalWrite(SLAVESELECT,LOW); //Select SPI device
    spi_transfer(register_name); //Send register location
    spi_transfer(register_value); //Send value to record into register

any help would be appreciated