Microchip MCP41xxx Digital Potentiometer Code Trouble

[CocaColaKid]

Can someone possibly explain to me why this code would not work? When I run it the digital pot does nothing.

    si      var     portb.2
    sclk    var     portb.1
    cs      var     portb.0

    pot_value   var     byte
    data_word   var     word

    low     sclk    ' Set clock pin low
    high    cs      ' Set chip select low

    clear
    
start:
    pot_value = pot_value + 1
    data_word.byte0 = %00010001     ' Set write instruction to potentiometer 0
    data_word.byte1 = pot_value     ' Set potentiometer value to be written
    gosub shout
    goto start                      

shout:
    low cs
    shiftout si,sclk,1,[data_word\16]   ' Shift 16 bits out starting at bit0
    high cs
    return