how to program digital potensiometer AD5260

Hello everyone I need to program digital potentiometer AD5260,
It's volatile memory and use SPI.
I connect the pin llike this :
Pin1 A +15Volt
Pin2 W Output
Pin3 – B- Ground
Pin4 VDD +15Volt
Pin5 SHDN +15Volt
Pin6 CLK Pin 13 Arduino
Pin7 SDI Pin 11 Arduino
Pin8 CS Pin 10 Arduino
Pin9 PR +15Volt
Pin10 GND Ground
Pin11 -VSS-Ground
Pin12 VL +5Volt
Pin13 -NC-No Connect
Pin14 -SDO-Pin 12 Arduino

And use the code below:
#include “SPI.h” // necessary library
int ss=10; // using digital pin 10 for SPI slave select
int del=200; // used for various delays

void setup()
{ 
  pinMode(ss, OUTPUT); // for SS pin 
  SPI.begin(); // wake up the SPI bus. 
  SPI.setBitOrder(MSBFIRST); //ent MSB (most significant byte) first
}

void setValue(int value)
{ 
  digitalWrite(ss, LOW); 
  SPI.transfer(0); // send command byte 
  SPI.transfer(value); // send value (0~255) 
  digitalWrite(ss, HIGH);
}

void loop()
{ 
  for (int a=0; a<256; a++) 
  { 
     setValue(a); 
     delay(del); 
  } 
  for (int a=255; a>=0; —a) 
  { 
     setValue(a); 
     delay(del); }
}

But it won't work, the output on W still stuck on the midpoint, around 7,27 Volt.

Welcome on the Arduino board, please modify your post , select the code part and press the # button above the smileys to get proper code tags.
It will look more readable that way.

what if you set it to a fixed value?

#include “SPI.h” 

const int ss = 10;       // using digital pin 10 for SPI slave select
const int del = 200; 

void setup()
{ 
  pinMode(ss, OUTPUT); 
  SPI.begin();
  SPI.setBitOrder(MSBFIRST);

  setValue(a); 
}

void setValue(int value)
{ 
  digitalWrite(ss, LOW); 
  SPI.transfer(0); // send command byte 
  SPI.transfer(value); // send value (0~255) 
  digitalWrite(ss, HIGH);
}

void loop()
{
}

Thank you for answering my question and noticing my post Rob,
I did try this method, but it still didn't work,
Am i connect the pin to the wrong connection?
I've tried AD8402 before, the program works fine,
But it didn't in AD5260.
Please help me.

#include “SPI.h” 

const int ss = 10;       // using digital pin 10 for SPI slave select
const int del = 200; 

void setup()
{ 
  pinMode(ss, OUTPUT); 
  SPI.begin();
  SPI.setBitOrder(MSBFIRST);

  setValue(200); 
}

void setValue(int value)
{ 
  digitalWrite(ss, LOW); 
  SPI.transfer(value);  
  digitalWrite(ss, HIGH);
}

void loop()
{
}

Can you give it a try?