fail to connect multiple I2C sensors

I want to connect two sensors (MPU-6050, CJMCJ-43) on EDISON FOR ARDUINO* BOARD.

When I enable one of them, it works well. But when I connect both into SCL/SDA, only one (CJMCJ-43) is accesible.

I use the mraa library which connect the sensors via I2C-smbus protocol.

int tempAddr = 0x68;
int opticalAddr = 0x23;

void test_mraa()
{
      mraa_i2c_context i2c;
      i2c = mraa_i2c_init(6);
 
      int tempAddr = 0x68;
     
      char txbuf[1];
      char rxbuf[1];
      // init temp sensor
      txbuf[0] = 0x75; 
      mraa_i2c_address(i2c, tempAddr);
      mraa_i2c_write(i2c, txbuf, 1);//On error "Failed to write to i2c" returned
      mraa_i2c_address(i2c, tempAddr);
      mraa_i2c_read(i2c, rxbuf, 1);
 
      if (rxbuf[0] != 0x68)
          printf("No MPU-6050");

   mraa_i2c_address(i2c, opticalAddr);
      txbuf[0] = 0x01;     // power on
      mraa_i2c_write(i2c, txbuf, 1);
}