Put the E-collar on my 8 month old BLF yesterday. I started on the lowest setting (Sportdog 400) I had her on a lead and I started introducing her to the collar with Sit. I never really saw any response to the collar and I had it up to 3. Do I keep going higher to get a response? She is a pretty hard-headed dog and can take quite a bit of pressure so maybe I need a different collar? any suggestions help!