Xbee Pro S1 adjust Power Aplifier


I am programming an Xbee Pro S1 using the SMAC codebase. I have seen that this module has a digital potentiometer used to adjust the output power of the XBee Pro but I am not able to change the value of this potentiometer.

This is the code provided for Xbee Pro to write using SPI the digital potentiometer but is not working:

void POT_Write(UINT8 value) {
while(!SPI1S_SPTEF); //Wait for TX Buffer Empty Flag
PTAD_PTAD3 = 0; //DIG_POT_CS low
SPI1D = value; // Write Addr byte
while (!SPI1S_SPTEF); //Wait again for TX Buffer Empty Flag

//A little time is needed after the data
//is clocked in and before CE is deasserted to allow the POT
//to operate properly. Each nop is based on a 16 Mhz clock.
//The amount of time was empirically determined. A timer would be
//a better option given that the MCU clock could change.
__asm nop; __asm nop; __asm nop; __asm nop; __asm nop;
__asm nop; __asm nop; __asm nop; __asm nop; __asm nop;

// set A3/DIG_POS_~CS high to disable writing to the digital potentiometer
// as CS rises, the digital pot loads its register with the clocked in byte value

It would be better if you had mentioned the explaination for this in depth, how code is working and which parameter on XBee it is setting and which parameter it is reading