I have portb.4 going out to a camera controller. The pin is held high with a 10k resistor. In order to turn the camera on, I have to take the pin to ground for about 200ms. It seems to work a couple of times and then stops working. I've tried to monitor the pin with an O-scope, and it doesn't appear to be going low. I wrote a real simple program to test.

loop:
if portb.1 = 1 then
low portb.4
pause 200
high portb.4
goto loop
endif

I'm using a 16F628. I've tried another pic to make sure I haven't damaged the original. It seems strange though that it will work once or twice and then stop. I also removed the camera from the equation and just put my scope on the pin. Same thing...goes low once or twice and then stays high. Maybe there is an electrical issue here I'm missing.