ADC With a BX-24

I am using a BX-24 because I am short on PICs and for my processing final, I am using analgue input.

Here is the schematic from Tom Igoe's site for the BX-24:



This is the first program I tried on the BX-24:

dim potVar as integer

Sub main()
call delay(0.5) ' start program with a half-second delay

do
potVar = getADC(13)
debug.print "potVar = " ; cstr(potVar)
loop

end sub


For some reason,the BX-24 returns really clean values from the potentiometer.