It always helps to indicate which PICAXE you are using, which version of the Programming Editor, and exactly what you are trying to do - "could not activate the porta pins" leaves people having to guess what you actually mean, it may be clear to you but not to anyone else.
I'm guessing you're using a 28X and when you use "IF PORTA pinX" there's no simulator button to be able to toggle those port pins on and off.
You could log that as a deficiency in the Software Feedback forum and in the meantime, the "IF PORTA pinX" will read the pin high when the analogue voltage in is set to greater than 127 for the particular pin, and low when below. Adjust the ADC value to alter the digital pin reading.
