Translation of Hauptsache

I need to write you one more sentence. This is what my teacher told me and the German language is so difficult. So please, as a last favor, would you please write the sentence for me in German?
My web designer found a bug and fixed it. Please ignore the last email. There seems to be a misunderstanding: When a user clicks on the Demo button, our cookie will automatically be set. That's it.
Unfortunately, the boat's maneuvering system broke down and we were told that we could not take it. We were furious, but decided to make the best out of the situation. The offered to take the Red Dragon instead.