BW, I just got mine out of the wardrobe and mucked around with it because I couldn't remember whether it clicked as you depressed the button or not. It does make a rapid clicking sound as you do that.

Chances are that if you felt the dosage go in both times (it was a coolish sensation as I recall) then you are doing it right. I think the pen is pretty foolproof in that regard.

Give them a ring though if you are worried. Good luck.

Mel