I had a new pen the dial did not click when dialed and the plunger would not go in or even budge. I took another from the box, same thing. After the third pen I had insulin. It was a Sunday night and I am so glad I had pens on hand. What would happen if it were my last new pen and would not inject. I called the company and am sending the pens back for review. It is a very expensive proposition when one fails. HAVE YOU HAD A PROBLEM?