Hey Butch,
I've never used the "SYMBOL" instruction, so don't have any idea if this could be a problem or not, but I read this in the PBP manual:

"SYMBOL provides yet another method for aliasing variables and
constants. It is included for BS1 compatibility.
>> SYMBOL cannot be used to create a variable. Use VAR to create a variable."

Maybe try this instead:

; Set Variables and aliases as needed.
CAMPOW VAR GPIO.0
volt VAR GPIO.1


Arch