Please clarify my thoughts, here. I'm a complete newcomer to this controller (DMC30016)

I am trying to trigger a data acquisition box with a low-edge pulse. I thought if I simply did
OP $0F ;' set all pins high just because?
SB 2 ;Set pin to start with
<do some other stuff>
#LOOP
CB 2 ;'set pin low
WT 1000 ;' Wait a full second
SB 2 ;' Set pin high again
WT 1000
JP #LOOP
EN

I should see a square wave with a frequency with a two-second interval.

I am not seeing this. I am not seeing anything on the output. I've tried this with bits 1, 2, and 4 with the same results (one can never tell if a prior user of the controller had fried one of the outputs. Unlikely that they'd fried three of them).

Do I need other control code? Do I need a pullup on the pin? Do I misunderstand the meaning of set and clear?

Thanks in advance!
John