drive multiple DFRobot BH1750 light sensor with Arduino microcontroller

Hi,
I’m currently working on BH1750 light sensor, it’s worked fine in single device with I2C address 0x23, but I’ve a problem if I used it in series of multiple devices. The address can’t changes to 0x5C, even ADD pin connected to the GND or internal pull-up resistor (4.7K). Can DFRobot provide some examples of wiring and coding with it? Here my current wiring and coding.

Code :
[code]#include <Wire.h>
#include <math.h>
int Sen1 = 0x23;
int Sen2 = 0x5C;

byte buff[2];

void setup()
{
Wire.begin();
Serial.begin(57600);
}

void loop()
{
uint16_t val1=0, val2=0;

BH1750_Init(Sen1);
delay(200);

if(2==BH1750_Read(Sen1))
{
val1=((buff[0]<<8 )|buff[1])/1.2;
Serial.print(val1,DEC);
Serial.println("[lx]");
}
delay(200);

BH1750_Init(Sen2);
delay(200);

if(2==BH1750_Read(Sen2))
{
val2=((buff[0]<<8 )|buff[1])/1.2;
Serial.print(val2,DEC);
Serial.println("[lx]");
}
delay(200);
}

int BH1750_Read(int address)
{
int i=0;
Wire.beginTransmission(address);
Wire.requestFrom(address, 2);
while(Wire.available()) //
{
buff = Wire.read();
i++;
}
Wire.endTransmission();
return i;
}

void BH1750_Init(int address)
{
Wire.beginTransmission(address);
Wire.write(0x10);
Wire.endTransmission();
}[/code]

The link of the sensor: [url=http://www.dfrobot.com/index.php?route=product/product&filter_name=bh1750&product_id=531#.USHliaWePvN]http://www.dfrobot.com/index.php?route=product/product&filter_name=bh1750&product_id=531#.USHliaWePvN[/url]