LCD using MCP23017 i2C

Oke, I've taken a look in the library of Nick gammon in which I found something which could cause my problem.

void I2C_graphical_LCD_display::cmd (const byte data)
{
  startSend ();
    doSend (GPIOA);                      // control port
    doSend (LCD_RESET | LCD_ENABLE | _chipSelect);   // set enable high (D/I is low meaning instruction) 
    doSend (data);                       // (command written to GPIOB)
    doSend (LCD_RESET | _chipSelect);    // (GPIOA again) pull enable low to toggle data 
  endSend ();
} // end of I2C_graphical_LCD_display::cmd

The code before the comment on the 5th line is what takes my attention. When I look at the lcd's database the pin mapping port D/I is at pin 16, but the comment which follows tells me that low is meaning Data and high is instruction.

Anyone who can tell me how to swap this?
Probably there are more problems in the code in relation to my lcd screen.
Regards,
Niels

Schermafbeelding 2012-08-24 om 20.59.04.png