Mite, I'm not surprised. There are days that my dog will react to level 1 and others where she will completely ignore it. I've noticed the more focused she is with something the more level I have to add to the correction. I appreciate how you are approaching the collar though. I've been with guys who will light up there dog with the first correction and then laugh about it. These are also probably the same people who were picked on in school when they were kids.
Keep up the slow and steady approach and you will be very rewarded in the end.